weekly contest 351

Author: ZLBer

Diff for: README.md

@@ -62,6 +62,8 @@ leetcode url: <https://leetcode.cn/u/cctest/>
 * 🐶 [weekly contest 290](src/main/java/weekly/wk290.java)
 * 🐭 [weekly contest 280](src/main/java/weekly/wk289.java)
 
+
+* 🐸 [biweekly contest 107](src/main/java/weekly/wkb107.java)   暴力 | 找规律 | 记忆化搜索、dp | 滑动窗口
 * 🐸 [biweekly contest 106](src/main/java/weekly/wkb106.java)   模拟 | 滑动窗口 | 排序统计 | 贪心
 * 🐸 [biweekly contest 105](src/main/java/weekly/wkb105.java)   模拟 | 记忆化搜索 | 分类讨论 | 并查集
 * 🐸 [biweekly contest 102](src/main/java/weekly/wkb102.java)   模拟 | 前缀和 | bfs+dfs | Dijkstra

Diff for: src/main/java/weekly/wkb107.java

@@ -0,0 +1,148 @@
+package weekly;
+
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+
+public class wkb107 {
+
+    //暴力
+    //字符串长度是2，可以不用这么麻烦
+    public int maximumNumberOfStringPairs(String[] words) {
+        int ans = 0;
+        Set<Integer> set = new HashSet<>();
+        for (int i = 0; i < words.length; i++) {
+            if (set.contains(i)) continue;
+            for (int j = i + 1; j < words.length; j++) {
+                if (set.contains(j)) continue;
+                String word = words[j];
+                String rs = new StringBuilder(word).reverse().toString();
+                if (words[i].equals(rs)) {
+                    ans++;
+                    set.add(i);
+                    set.add(j);
+                }
+            }
+        }
+        return ans;
+    }
+
+
+    //找规律
+    public int longestString(int x, int y, int z) {
+        int ans = 0;
+        int min = Math.min(x, y);
+
+
+        //按照 min*(AA+BB)+z*AB 拼接
+
+        ans += 4 * min + z * 2;
+
+        //剩下的 AA或BB
+        int left = Math.max(x, y) - min;
+        boolean flag = true;
+
+        //若之前有AA或BB 且 还有剩下的，那么就可以把AA放在最后或者把BB放在最前面
+        if (x == 0 || y == 0) {
+            flag = false;
+        }
+        if (left > 0 && flag) {
+            ans += 2;
+        }
+        return ans;
+    }
+
+
+    //记忆化搜索
+    public int minimizeConcatenatedLength(String[] words) {
+        memo = new int[words.length][26 * 26];
+        for (int[] ints : memo) {
+            Arrays.fill(ints, -1);
+        }
+        return help(words[0].charAt(0), words[0].charAt(words[0].length() - 1), 1, words) + words[0].length();
+    }
+
+    int[][] memo;
+
+    int help(char left, char right, int index, String[] words) {
+        if (index >= words.length) {
+            return 0;
+        }
+        int key = (left - 'a') * 26 + (right - 'a');
+
+        if (memo[index][key] != -1) {
+            return memo[index][key];
+        }
+
+        String word = words[index];
+        int len = Integer.MAX_VALUE;
+        //放在左边
+        int l = 0;
+        if (word.charAt(word.length() - 1) == left) {
+            l = 1;
+        }
+        len = Math.min(help(word.charAt(0), right, index + 1, words) + word.length() - l, len);
+
+        //放在右边
+        int r = 0;
+        if (word.charAt(0) == right) {
+            r = 1;
+        }
+        len = Math.min(len, help(left, word.charAt(word.length() - 1), index + 1, words) + word.length() - r);
+
+        memo[index][key] = len;
+        return len;
+    }
+
+
+
+
+    //滑动窗口
+  static   public int[] countServers(int n, int[][] logs, int x, int[] queries) {
+        int[][] qq = new int[queries.length][2];
+        for (int i = 0; i < queries.length; i++) {
+            qq[i] = new int[]{queries[i] - x, queries[i], i};
+        }
+        Arrays.sort(qq, (a, b) -> a[0] - b[0]);
+        Arrays.sort(logs, (a, b) -> a[1] - b[1]);
+
+        int right=0;
+        int left=0;
+        Map<Integer,Integer> counter=new HashMap<>();
+        int []res=new int[queries.length];
+        for (int i = 0; i < qq.length; i++) {
+            int l=qq[i][0];
+            int r=qq[i][1];
+
+            //向右滑到查询的截止时间
+            while (right<logs.length&&logs[right][1]<=r){
+                counter.put(logs[right][0],counter.getOrDefault(logs[right][0],0)+1);
+                right++;
+            }
+
+            //左边开始滑动到查询的开始时间
+            while (left<logs.length&&logs[left][1]<l){
+                Integer count = counter.get(logs[left][0]);
+                if(count==1){
+                    counter.remove(logs[left][0]);
+                }else {
+                    counter.put(logs[left][0],count-1);
+
+                }
+                left++;
+            }
+
+            res[qq[i][2]]=n-counter.size();
+        }
+        return res;
+
+    }
+
+    public static void main(String[] args) {
+        countServers(3,new int[][]{
+                {1,3},{2,6},{1,5}
+        },5,new int[]{10,11});
+    }
+}