weekly contest 325

Author: ZLBer

README.md

@@ -5,6 +5,7 @@ Record leetcode contest and ideas every week, and encourage yourself to think mo
 leetcode url: <https://leetcode.cn/u/cctest/>
 
 
+* 🐎️ [weekly contest 325](src/main/java/weekly/wk325.java)     数学 | 数学 | 动态规划 | 数学
 * 🐎️ [weekly contest 324](src/main/java/weekly/wk324.java)     位运算 | 数学 | 图 | 完全二叉树性质
 * 🐎️ [weekly contest 323](src/main/java/weekly/wk323.java)     排序 | 哈希 | 模拟 | 最小堆、Dijkstra最短路径
 * 🐎️ [weekly contest 322](src/main/java/weekly/wk322.java)     遍历 | 排序 | BFS | 二分图+BFS

src/main/java/weekly/wk325.java

@@ -0,0 +1,108 @@
+package weekly;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+public class wk325 {
+
+    //ranking: 917 / 3873
+
+    //直接做就好了
+    public int countDigits(int num) {
+        int c = num;
+        int ans = 0;
+        while (c > 0) {
+
+            if (num % (c % 10) == 0) {
+                ans++;
+            }
+            c /= 10;
+        }
+        return ans;
+    }
+
+     //计算质因数
+    public int distinctPrimeFactors(int[] nums) {
+        Set<Integer> set = new HashSet<>();
+        for (int num : nums) {
+            for (int i = 2; i*i<=num; i++) {
+                while (num % i == 0) {
+                    num /= i;
+                    set.add(i);
+                }
+
+            }
+            if (num>1){
+                set.add(num);
+            }
+        }
+        return set.size();
+    }
+
+
+    //用dp做，也可以贪心
+    public int minimumPartition(String s, int k) {
+
+        int[] dp = new int[s.length() + 1];
+
+        Arrays.fill(dp, (int) 1e9 + 7);
+        dp[0] = 0;
+
+        for (int left = 0; left < s.length(); left++) {
+            long sum = 0;
+            for (int right = left; right < s.length(); right++) {
+                sum = sum * 10 + s.charAt(right) - '0';
+                if (sum <= k) {
+                    dp[right + 1] = Math.min(dp[right + 1], dp[left] + 1);
+                } else {
+                    break;
+                }
+            }
+        }
+        return dp[s.length()] == (int) 1e9 + 7 ? -1 : dp[0];
+    }
+
+
+    //预处理所有质数(埃氏筛)+计算质数间隔
+    public int[] closestPrimes(int left, int right) {
+
+        boolean[] prime = isPrime(right);
+        List<Integer> list = new ArrayList<>();
+        for (int i = 0; i < prime.length; i++) {
+            if (prime[i] && i >= left && i <= right) {
+                list.add(i);
+            }
+        }
+        if (list.size() < 2) return new int[]{-1, -1};
+        int min = Integer.MAX_VALUE;
+        int[] ans = new int[2];
+
+        for (int i = 1; i < list.size(); i++) {
+            if (list.get(i) - list.get(i - 1) < min) {
+                min = list.get(i) - list.get(i - 1);
+                ans = new int[]{list.get(i-1), list.get(i )};
+            }
+        }
+        return ans;
+    }
+
+    public static boolean[] isPrime(int n) {
+        boolean[] arr = new boolean[n + 1];
+        // 1:质数   0:非质数
+        Arrays.fill(arr, true);
+        arr[1]=false;
+        for (int i = 2; i <= n; i++) {
+            if (arr[i]) {
+                // 将i的倍数去除掉
+                for (int j = i + i; j <= n; j += i) {
+                    arr[j] = false;
+                }
+            }
+        }
+        return arr;
+    }
+
+}