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weekly contest 341
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‎README.md‎

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@@ -6,6 +6,8 @@ leetcode url: <https://leetcode.cn/u/cctest/>
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* ☀️ [weekly contest 341](src/main/java/weekly/wk341.java) 模拟 | 美剧 | 贪心 | 树形dp
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* ☀️ [weekly contest 340](src/main/java/weekly/wk340.java) 模拟 | 哈希 | 贪心 | bfs+优化
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* ☀️ [weekly contest 339](src/main/java/weekly/wk339.java) 模拟 | 哈希 | 贪心 | 平衡树
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* ☀️ [weekly contest 338](src/main/java/weekly/wk338.java) 贪心 | 谈心 | 前缀和+二分 | 拓扑排序
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* ☀️ [weekly contest 337](src/main/java/weekly/wk337.java) 模拟 | 模拟 | 回溯 | 同余分组
@@ -54,6 +56,8 @@ leetcode url: <https://leetcode.cn/u/cctest/>
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* 🐶 [weekly contest 290](src/main/java/weekly/wk290.java)
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* 🐭 [weekly contest 280](src/main/java/weekly/wk289.java)
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* 🐸 [biweekly contest 102](src/main/java/weekly/wkb102.java) 模拟 | 前缀和 | bfs+dfs | Dijkstra
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* 🐸 [biweekly contest 101](src/main/java/weekly/wkb101.java) 哈希 | 滑动窗口 | 并查集 | BFS
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* 🐸 [biweekly contest 100](src/main/java/weekly/wkb100.java) 四维 | 贪心 | 堆 | 二分
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* 🐸 [biweekly contest 99](src/main/java/weekly/wkb99.java) 贪心 | 递推 | 区间合并 | 换根DP

‎src/main/java/weekly/wk340.java‎

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package weekly;
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import java.util.ArrayDeque;
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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.Deque;
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import java.util.HashMap;
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import java.util.HashSet;
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import java.util.LinkedList;
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import java.util.List;
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import java.util.Map;
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import java.util.Queue;
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import java.util.Set;
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public class wk340 {
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public static boolean isPrime(int n) {
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if (n == 0 || n == 1) {
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return false;
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}
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for (int i = 2; i <= (int) Math.sqrt(n); i++) {
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if (n % i == 0) {
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return false;
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}
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}
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return true;
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}
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//求质数
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public int diagonalPrime(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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if (isPrime(nums[i][i])) {
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ans = Math.max(nums[i][i], ans);
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}
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if (isPrime(nums[i][nums.length - i - 1])) {
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ans = Math.max(nums[i][nums.length - i - 1], ans);
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}
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}
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return ans;
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}
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// 哈希分组+计算增量或前缀和
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public long[] distance(int[] nums) {
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long[] arr = new long[nums.length];
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Map<Integer, List<Integer>> map = new HashMap<>();
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for (int i = 0; i < nums.length; i++) {
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if (!map.containsKey(nums[i])) map.put(nums[i], new ArrayList<>());
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map.get(nums[i]).add(i);
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}
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for (List<Integer> list : map.values()) {
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long sum = 0;
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for (int i = 1; i < list.size(); i++) {
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sum += list.get(i) - list.get(0);
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}
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//最左侧直接求差值和
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arr[list.get(0)] = sum;
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for (int i = 1; i < list.size(); i++) {
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long dis = list.get(i) - list.get(i - 1);
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//增加了i个dis，减少了(list.size-i)个ids
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sum += (i - (list.size() - i)) * dis;
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arr[list.get(i)] = sum;
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}
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}
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return arr;
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}
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/* static public int minimizeMax(int[] nums, int p) {
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PriorityQueue<int[]> priorityQueue = new PriorityQueue<>((a, b) -> a[0] - b[0]);
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Arrays.sort(nums);
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for (int i = 1; i < nums.length; i++) {
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priorityQueue.add(new int[]{nums[i] - nums[i - 1], i - 1, i});
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}
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Set<Integer> set = new HashSet<>();
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int ans=0;
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while (p > 0) {
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int[] cur = priorityQueue.poll();
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if (!set.contains(cur[1]) && !set.contains(cur[2])) {
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set.add(cur[1]);
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set.add(cur[2]);
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ans=Math.max(cur[0],ans);
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int left=cur[1]-1;
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int right=cur[2]+1;
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if(left>=0&&right<nums.length){
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priorityQueue.add(new int[]{nums[right]-nums[left],left,right});
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}
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p--;
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}
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}
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return ans;
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}*/
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//最大化最小 考虑二分
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static public int minimizeMax(int[] nums, int p) {
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Arrays.sort(nums);
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int left = 0, right = nums[nums.length - 1] - nums[0];
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while (left < right) {
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int mid = (left + right) / 2;
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if (check(nums, mid, p)) {
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right = mid;
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} else {
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left = mid + 1;
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}
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}
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return left;
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}
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static boolean check(int[] nums, int mid, int p) {
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Deque<Integer> deque = new ArrayDeque<>();
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int ans = 0;
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for (int i = 0; i < nums.length; i++) {
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if (!deque.isEmpty()) {
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if (nums[i] - deque.peekLast() <= mid) {
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ans++;
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deque.pollLast();
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} else {
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deque.addLast(nums[i]);
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}
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} else {
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deque.addLast(nums[i]);
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}
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}
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return ans >= p;
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}
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//记录每次每行每列到达的最大位置
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public int minimumVisitedCells(int[][] grid) {
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Queue<int[]> queue = new LinkedList<>();
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queue.add(new int[]{0, 0});
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int m = grid.length;
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int n = grid[0].length;
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int[] maxBelow = new int[n];
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int[] maxRight = new int[m];
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Set<Integer> set = new HashSet<>();
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int step = 1;
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set.add(0);
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while (!queue.isEmpty()) {
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int size = queue.size();
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while (size-- > 0) {
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int[] cur = queue.poll();
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if (cur[0] == m - 1 && cur[1] == n - 1) {
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return step;
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}
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int k = grid[cur[0]][cur[1]];
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int belowM = Math.min(m - 1, cur[0] + k);
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int rightM = Math.min(n - 1, cur[1] + k);
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//取最大值，因为可能到不了cur[0]这个位置
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int begin=Math.max(maxBelow[cur[1]],cur[0]);
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for (int i = begin; i <= belowM; i++) {
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int nx = i, ny = cur[1];
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if(set.contains(nx * n + ny)) continue;
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set.add(nx * n + ny);
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queue.add(new int[]{nx, ny});
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}
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//取最大值，因为可能到不了cur[1]这个位置
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begin=Math.max(maxRight[cur[0]],cur[1]);
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for (int i = begin; i <= rightM; i++) {
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int nx = cur[0], ny = i;
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if(set.contains(nx * n + ny)) continue;
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set.add(nx * n + ny);
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queue.add(new int[]{nx, ny});
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}
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maxBelow[cur[1]]=Math.max(belowM,maxBelow[cur[1]]);
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maxRight[cur[0]]=Math.max(rightM,maxRight[cur[0]]);
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}
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step++;
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}
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return -1;
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}
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public static void main(String[] args) {
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minimizeMax(new int[]{2, 4, 1, 2}, 1);
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}
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}

‎src/main/java/weekly/wk341.java‎

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package weekly;
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import sun.security.krb5.internal.APRep;
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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.LinkedList;
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import java.util.List;
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import java.util.Map;
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import java.util.Queue;
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import java.util.Set;
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public class wk341 {
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//模拟
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public int[] rowAndMaximumOnes(int[][] mat) {
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int ans = 0;
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int count = 0;
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for (int i = 0; i < mat.length; i++) {
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int c = 0;
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for (int j = 0; j < mat[0].length; j++) {
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if (mat[i][j] == 1) {
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c++;
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}
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}
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if (c > count) {
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count = c;
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ans = i;
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}
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}
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return new int[]{ans, count};
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}
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//枚举
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public int maxDivScore(int[] nums, int[] divisors) {
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int[] score = new int[divisors.length];
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for (int i = 0; i < divisors.length; i++) {
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int count = 0;
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for (int j = 0; j < nums.length; j++) {
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if (nums[j] % divisors[i] == 0) {
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count++;
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}
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}
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score[i] = count;
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}
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int max = 0;
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int ans = Integer.MAX_VALUE;
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for (int i = 0; i < score.length; i++) {
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if (score[i] > max) {
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ans = divisors[i];
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max = score[i];
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} else if (score[i] == max && divisors[i] < ans) {
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ans = divisors[i];
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}
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}
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return ans;
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}
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//贪心，尽量用之前没有用完的字母
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static public int addMinimum(String word) {
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char pre = 'c';
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int ans = 0;
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for (int i = 0; i < word.length(); i++) {
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char c = word.charAt(i);
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//前面结束
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if (pre == 'c') {
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ans += c - 'a';
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pre = c;
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} else {
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if (c > pre) {
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ans += c - pre - 1;
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pre = c;
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} else {
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//表示前面的需要结束，重新开始
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ans += 'c' - pre;
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pre = 'c';
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i--;
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}
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}
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}
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ans += 'c' - pre;
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return ans;
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}
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//转换成count数组然后树形dp
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public int minimumTotalPrice(int n, int[][] edges, int[] price, int[][] trips) {
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Map<Integer, List<Integer>> map = new HashMap<>();
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for (int[] edge : edges) {
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if (!map.containsKey(edge[0])) map.put(edge[0], new ArrayList<>());
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if (!map.containsKey(edge[1])) map.put(edge[1], new ArrayList<>());
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map.get(edge[0]).add(edge[1]);
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map.get(edge[1]).add(edge[0]);
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}
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int[] count = new int[n];
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for (int[] trip : trips) {
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dfs(map, count, trip[0], trip[1], -1);
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}
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int[] ans = dfs2(map, count, price, 0, -1);
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return Math.min(ans[0], ans[1]);
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}
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boolean dfs(Map<Integer, List<Integer>> map, int[] count, int cur, int target, int parent) {
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if (cur == target) {
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count[cur]++;
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return true;
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}
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for (Integer next : map.getOrDefault(cur, new ArrayList<>())) {
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if (next == parent) continue;
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//是路径上的点
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if (dfs(map, count, next, target, cur)) {
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count[cur]++;
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return true;
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}
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}
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return false;
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}
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int[] dfs2(Map<Integer, List<Integer>> map, int[] count, int[] price, int cur, int parent) {
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int[] ans = new int[]{price[cur] * count[cur], price[cur] * count[cur]/2};
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int childMaxSum = 0;
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int childNoSum = 0;
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for (Integer next : map.getOrDefault(cur, new ArrayList<>())) {
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if (next == parent) continue;
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int[] child = dfs2(map, count, price, next, cur);
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childMaxSum += Math.min(child[0], child[1]);
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childNoSum += child[0];
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}
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ans[0] += childMaxSum;
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ans[1] +=childNoSum;
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return ans;
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}
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public static void main(String[] args) {
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wk341 w = new wk341();
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w.minimumTotalPrice(4, new int[][]{{0, 1}, {1, 2}, {1, 3}}, new int[]{2, 2, 10, 6}, new int[][]{{0, 3}, {2, 1}, {2, 3}});
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}
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}

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