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weekly contest 353
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Diff for: ‎README.md

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@@ -4,7 +4,8 @@ Record leetcode contest and ideas every week, and encourage yourself to think mo
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leetcode url: <https://leetcode.cn/u/cctest/>
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7-
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* ☀️ [weekly contest 353](src/main/java/weekly/wk353.java) 贪心 | dp | dp | 差分数组
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* ☀️ [weekly contest 352](src/main/java/weekly/wk352.java) 模拟 | 质数 | 滑动窗口 | 枚举
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* ☀️ [weekly contest 350](src/main/java/weekly/wk350.java) 模拟 | 排序 | 状态压缩 | dp、记忆化
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* ☀️ [weekly contest 349](src/main/java/weekly/wk349.java) 模拟 | 贪心 | dp | 堆、单调栈
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* ☀️ [weekly contest 348](src/main/java/weekly/wk348.java) 哈希 | 分类讨论 | 逆向 | 数位DP
@@ -63,6 +64,7 @@ leetcode url: <https://leetcode.cn/u/cctest/>
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* 🐭 [weekly contest 280](src/main/java/weekly/wk289.java)
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* 🐸 [biweekly contest 108](src/main/java/weekly/wkb108.java) 模拟 | 哈希 | dp | 枚举
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* 🐸 [biweekly contest 107](src/main/java/weekly/wkb107.java) 暴力 | 找规律 | 记忆化搜索、dp | 滑动窗口
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* 🐸 [biweekly contest 106](src/main/java/weekly/wkb106.java) 模拟 | 滑动窗口 | 排序统计 | 贪心
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* 🐸 [biweekly contest 105](src/main/java/weekly/wkb105.java) 模拟 | 记忆化搜索 | 分类讨论 | 并查集

Diff for: ‎src/main/java/weekly/wk352.java

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package weekly;
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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.HashSet;
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import java.util.List;
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import java.util.Set;
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import java.util.TreeMap;
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import java.util.TreeSet;
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public class wk352 {
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//o(n)也可以，因为具有单一性
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public int longestAlternatingSubarray(int[] nums, int threshold) {
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int ans = 0;
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for (int i = 0; i < nums.length; i++) {
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if (nums[i] % 2 != 0 || nums[i] > threshold) continue;
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int max = 1;
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for (int j = i + 1; j < nums.length; j++) {
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if (nums[j] % 2 == nums[j - 1] % 2) {
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break;
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}
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if (nums[j] > threshold) {
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break;
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}
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max++;
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}
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ans = Math.max(ans, max);
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}
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return ans;
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}
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public static List<Integer> getPrimes(int n) {
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boolean[] isComposite = new boolean[n + 1];
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List<Integer> primes = new ArrayList<>();
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for (int i = 2; i <= n; i++) {
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if (!isComposite[i]) {
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primes.add(i);
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for (int j = i * 2; j >= 0 && j <= n; j += i) { // 标记该数的倍数为合数
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isComposite[j] = true;
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}
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}
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}
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return primes;
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}
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static Set<Integer> set = new HashSet<>();
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static {
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for (Integer prime : getPrimes(1000001)) {
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set.add(prime);
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}
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}
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//先static求出所有质数
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public List<List<Integer>> findPrimePairs(int n) {
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List<List<Integer>> res = new ArrayList<>();
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for (int i = 2; i <= n / 2; i++) {
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if (set.contains(i) && set.contains(n - i)) {
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res.add(Arrays.asList(i, n - i));
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}
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}
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return res;
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}
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//滑动窗口,treemap存值方便找最大最小值
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static public long continuousSubarrays(int[] nums) {
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TreeMap<Integer, Integer> treeMap = new TreeMap<>();
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int left = 0;
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long ans = 0;
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for (int i = 0; i < nums.length; i++) {
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treeMap.put(nums[i], treeMap.getOrDefault(nums[i], 0) + 1);
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while (Math.abs(treeMap.firstKey() - treeMap.lastKey()) > 2) {
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Integer count = treeMap.get(nums[left]);
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if (count == 1) {
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treeMap.remove(nums[left]);
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} else {
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treeMap.put(nums[left], count - 1);
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}
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left++;
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}
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long c = (i - left + 1);
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ans += c;
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}
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return ans;
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}
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public static void main(String[] args) {
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continuousSubarrays(new int[]{5, 4, 2, 4});
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}
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// 枚举
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public int sumImbalanceNumbers(int[] nums) {
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int ans = 0;
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for (int i = 0; i < nums.length; i++) {
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int count = 0;
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TreeSet<Integer> treeSet = new TreeSet<>();
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treeSet.add(nums[i]);
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for (int j = i + 1; j < nums.length; j++) {
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if (treeSet.contains(nums[j])) {
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ans += count;
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continue;
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}
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Integer left = treeSet.lower(nums[j]);
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Integer right = treeSet.higher(nums[j]);
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if (left != null && right != null) {
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if (nums[j] - left > 1 && right - nums[j] > 1) {
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count++;
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} else if (nums[j] - left <= 1 && right - nums[j] <= 1) {
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count--;
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}
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} else if (left == null) {
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if (right - nums[j] > 1) {
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count++;
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}
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} else if (right == null) {
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if (nums[j] - left > 1) {
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count++;
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}
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}
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treeSet.add(nums[j]);
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ans += count;
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}
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}
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return ans;
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}
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}

Diff for: ‎src/main/java/weekly/wk353.java

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package weekly;
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import java.util.Arrays;
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import java.util.HashMap;
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import java.util.Map;
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public class wk353 {
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//贪心
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public int theMaximumAchievableX(int num, int t) {
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return num + t * 2;
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}
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//dp
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public int maximumJumps(int[] nums, int target) {
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int[] dp = new int[nums.length];
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Arrays.fill(dp, -1);
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dp[0] = 0;
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for (int i = 1; i < nums.length; i++) {
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for (int j = 0; j < i; j++) {
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if (nums[i] - nums[j] >= -target && nums[i] - nums[j] <= target && dp[j] != -1) {
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dp[i] = Math.max(dp[i], dp[j] + 1);
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}
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}
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}
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return dp[nums.length - 1];
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}
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//dp
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public int maxNonDecreasingLength(int[] nums1, int[] nums2) {
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int ans = 1;
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int[][] dp = new int[nums1.length][2];
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dp[0][0] = 1;
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dp[0][1] = 1;
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for (int i = 1; i < nums1.length; i++) {
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dp[i][0] = 1;
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dp[i][1] = 1;
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if (nums1[i] >= nums1[i - 1]) {
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dp[i][0] = Math.max(dp[i - 1][0] + 1, dp[i][0]);
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}
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if (nums1[i] >= nums2[i - 1]) {
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dp[i][0] = Math.max(dp[i - 1][1] + 1, dp[i][0]);
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}
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if (nums2[i] >= nums1[i - 1]) {
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dp[i][1] = Math.max(dp[i - 1][0] + 1, dp[i][1]);
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}
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if (nums2[i] >= nums2[i - 1]) {
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dp[i][1] = Math.max(dp[i - 1][1] + 1, dp[i][1]);
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}
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ans = Math.max(ans, dp[i][0]);
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ans = Math.max(ans, dp[i][1]);
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}
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return ans;
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}
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//滑动窗口 本质是差分数组
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static public boolean checkArray(int[] nums, int k) {
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if(k==1) return true;
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int sum = nums[0];
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for (int i = 1; i < nums.length; i++) {
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int left = i - k ;
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//减去左边的贡献
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if (left >= 0) {
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sum -= nums[left];
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}
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//需要减去更多，此处已经不满足
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if (sum > nums[i]) {
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return false;
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}
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//i处需要添加的贡献
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nums[i] = (nums[i] - sum);
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sum+=nums[i];
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}
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return nums[nums.length-1]==0;
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}
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public static void main(String[] args) {
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checkArray(new int[]{2,2,3,2,1},3);
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}
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}

Diff for: ‎src/main/java/weekly/wkb105.java

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@@ -148,7 +148,7 @@ public static List<Integer> getPrimes(int n) {
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for (int i = 2; i <= n; i++) {
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if (!isComposite[i]) {
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primes.add(i);
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for (int j = i * i; j >= 0 && j <= n; j += i) { // 标记该数的倍数为合数
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for (int j = i * 2; j >= 0 && j <= n; j += i) { // 标记该数的倍数为合数
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isComposite[j] = true;
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}
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}

Diff for: ‎src/main/java/weekly/wkb108.java

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package weekly;
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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.HashMap;
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import java.util.HashSet;
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import java.util.List;
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import java.util.Map;
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import java.util.Set;
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import java.util.TreeSet;
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public class wkb108 {
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//模拟
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public int alternatingSubarray(int[] nums) {
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int ans = 0;
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for (int i = 0; i < nums.length; i++) {
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int flag = 1;
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int j = i + 1;
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for (; j < nums.length; j++) {
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if (nums[j] - nums[j - 1] != flag) {
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break;
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}
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flag *= -1;
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}
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ans = Math.max(ans, j - i);
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}
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return ans == 1 ? -1 : ans;
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}
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//哈希
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public List<Integer> relocateMarbles(int[] nums, int[] moveFrom, int[] moveTo) {
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Set<Integer> set = new TreeSet<>();
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for (int i = 0; i < nums.length; i++) {
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set.add(nums[i]);
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}
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for (int i = 0; i < moveFrom.length; i++) {
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set.remove(moveFrom[i]);
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set.add(moveTo[i]);
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}
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List<Integer> res = new ArrayList<>(set);
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return res;
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}
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//dp
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public int minimumBeautifulSubstrings(String s) {
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int[] dp = new int[s.length() + 1];
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Arrays.fill(dp, (int) 1e9 + 7);
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dp[0] = 0;
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Set<String> set = new HashSet<>();
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int ans = 1;
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//先求出5的幂的2进制字符串
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for (int i = 0; i < 12; i++) {
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set.add(Integer.toBinaryString(ans));
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ans *= 5;
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}
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//dp枚举
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for (int i = 0; i < s.length(); i++) {
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for (int start = 0; start <= i; start++) {
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String sub = s.substring(start, i + 1);
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if (sub.startsWith("0")) continue;
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if (!set.contains(sub)) continue;
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dp[i + 1] = Math.min(dp[start] + 1, dp[i + 1]);
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}
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}
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return dp[s.length()] == (int) 1e7 ? -1 : dp[s.length()];
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}
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//枚举黑格子,每个格子只对四个有贡献，一次求对他们的贡献
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public long[] countBlackBlocks(int m, int n, int[][] coordinates) {
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Map<Long, Integer> map = new HashMap<>();
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for (int[] coordinate : coordinates) {
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//左上角
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int x = coordinate[0] - 1, y = coordinate[1] - 1;
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if (x >= 0 && y >= 0 && x < m && y < n) {
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long ans = (long) x * n + y;
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map.put(ans, map.getOrDefault(ans, 0) + 1);
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}
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//右上角
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x = coordinate[0] - 1;
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y = coordinate[1] + 1;
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if (x >= 0 && y >= 0 && x < m && y < n) {
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long ans = (long) x * n + y - 1;
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map.put(ans, map.getOrDefault(ans, 0) + 1);
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}
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//左下角
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x = coordinate[0] + 1;
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y = coordinate[1] - 1;
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if (x >= 0 && y >= 0 && x < m && y < n) {
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long ans = (long) (x - 1) * n + y;
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map.put(ans, map.getOrDefault(ans, 0) + 1);
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}
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//右下角
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x = coordinate[0] + 1;
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y = coordinate[1] + 1;
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if (x >= 0 && y >= 0 && x < m && y < n) {
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long ans = (long) (x - 1) * n + y - 1;
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map.put(ans, map.getOrDefault(ans, 0) + 1);
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}
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}
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long[] res = new long[5];
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long c = 0;
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for (int value : map.values()) {
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res[value]++;
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c++;
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}
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res[0] = (long) (m - 1) * (n - 1) - c;
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return res;
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}
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public static void main(String[] args) {
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}
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}

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