2024/9/27 Hot100 多维dp和每日一题

src/main/java/com/cool/hot100/multi_dp/Num64.java

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+package com.cool.hot100.multi_dp;
+
+/**
+ * Created with IntelliJ IDEA.
+ *
+ * @Author: Cool
+ * @Date: 2024/09/27/14:28
+ * DayNumber 2
+ * Hard 2
+ * Level ?
+ * @Description 64. 最小路径和
+ * @Link https://leetcode.cn/problems/minimum-path-sum/description/?envType=study-plan-v2&envId=top-100-liked
+ */
+public class Num64 {
+
+    public int minPathSum(int[][] grid) {
+        if(grid.length==0){
+            return 0;
+        }
+        int[][]dp=new int[grid.length][grid[0].length];
+        dp[0][0]=grid[0][0];
+        for(int i=1;i<grid.length;i++){
+            dp[i][0]=dp[i-1][0]+grid[i][0];
+        }
+        for(int i=1;i<grid[0].length;i++){
+            dp[0][i]=dp[0][i-1]+grid[0][i];
+        }
+        for(int i=1;i<grid.length;i++){
+            for(int j=1;j<grid[0].length;j++){
+                dp[i][j]=Math.min(dp[i-1][j],dp[i][j-1])+grid[i][j];
+            }
+        }
+        return dp[grid.length-1][grid[0].length-1];
+    }
+
+    /**
+     * 空间优化
+     * @param grid
+     * @return
+     */
+    public int minPathSum1(int[][] grid) {
+        if (grid.length == 0) {
+            return 0;
+        }
+
+        int rows = grid.length;
+        int cols = grid[0].length;
+        int[] dp = new int[cols];
+
+        dp[0] = grid[0][0];
+        for (int j = 1; j < cols; j++) {
+            dp[j] = dp[j - 1] + grid[0][j];
+        }
+        for (int i = 1; i < rows; i++) {
+            dp[0] += grid[i][0];
+            for (int j = 1; j < cols; j++) {
+                dp[j] = Math.min(dp[j], dp[j - 1]) + grid[i][j];
+            }
+        }
+        return dp[cols - 1];
+    }
+}

src/main/java/com/cool/one_question_per_day/LeetCode20240927.java

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+package com.cool.one_question_per_day;
+
+/**
+ * Created with IntelliJ IDEA.
+ *
+ * @Author: Cool
+ * @Date: 2024/09/27/09:02
+ * DayNumber 1
+ * Hard 2
+ * Level ?
+ * Score 1947
+ * @Description 2516. 每种字符至少取 K 个
+ * @Link https://leetcode.cn/problems/take-k-of-each-character-from-left-and-right/?envType=daily-question&envId=2024-09-27
+ */
+import org.junit.Test;
+
+import java.util.Arrays;
+
+public class LeetCode20240927 {
+    public int takeCharacters(String s, int k) {
+        char[] chars=s.toCharArray();
+        int[] arr = new int[3];
+        for(char c:chars){
+            //取走所有字符
+            arr[c-'a']++;
+        }
+        for(int num:arr){
+            if(num<k){
+                return -1;
+            }
+        }
+
+        int left = 0;
+        int res = 0;
+        for(int right=0;right<chars.length;right++){
+            int index=chars[right]-'a';
+            arr[index]--;
+            while(arr[index]<k){
+                arr[chars[left++]-'a']++;
+            }
+            res=Math.max(res,right-left+1);
+        }
+        return chars.length-res;
+    }
+    @Test
+    public void test(){
+        takeCharacters("aabaaaacaabc",2);
+    }
+}