三刷64

Author: diguage

docs/0064-minimum-path-sum.adoc

@@ -1,48 +1,36 @@
 [#0064-minimum-path-sum]
-= 64. Minimum Path Sum
+= 64. 最小路径和
 
-{leetcode}/problems/minimum-path-sum/[LeetCode - Minimum Path Sum^]
+https://leetcode.cn/problems/minimum-path-sum/[LeetCode - 64. 最小路径和 ^]
 
-Given a _m x n_ grid filled with non-negative numbers, find a path from top left to bottom right which _minimizes_ the sum of all numbers along its path.
+给定一个包含非负整数的 `m x n` 网格 `grid`，请找出一条从左上角到右下角的路径，使得路径上的数字总和为最小。
 
-*Note:* You can only move either down or right at any point in time.
+**说明：**每次只能向下或者向右移动一步。
 
-.Example:
-[source]
-----
-Input:
-[
-  [1,3,1],
-  [1,5,1],
-  [4,2,1]
-]
-Output: 7
-Explanation: Because the path 1→3→1→1→1 minimizes the sum.
-----
+*示例 1：*
 
-image::images/0064-1.png[{image_attr}]
+image::images/0064-01.jpg[{image_attr}]
 
-image::images/0064-2.png[{image_attr}]
+....
+输入：grid = [[1,3,1],[1,5,1],[4,2,1]]
+输出：7
+解释：因为路径 1→3→1→1→1 的总和最小。
+....
 
-思考题：尝试使用一维数组做备忘录来实现一下。
+*示例 2：*
 
-Given a _m_ x _n_ grid filled with non-negative numbers, find a path from top left to bottom right which _minimizes_ the sum of all numbers along its path.
+....
+输入：grid = [[1,2,3],[4,5,6]]
+输出：12
+....
 
-*Note:* You can only move either down or right at any point in time.
+*提示：*
 
-*Example:*
+* `+m == grid.length+`
+* `+n == grid[i].length+`
+* `+1 <= m, n <= 200+`
+* `+0 <= grid[i][j] <= 200+`
 
-[subs="verbatim,quotes,macros"]
-----
-*Input:*
-[
-  [1,3,1],
-  [1,5,1],
-  [4,2,1]
-]
-*Output:* 7
-*Explanation:* Because the path 1&rarr;3&rarr;1&rarr;1&rarr;1 minimizes the sum.
-----
 
 == 思路分析
 
@@ -66,6 +54,15 @@ include::{sourcedir}/_0064_MinimumPathSum.java[tag=answer]
 include::{sourcedir}/_0064_MinimumPathSum_2.java[tag=answer]
 ----
 --
+
+三刷::
++
+--
+[{java_src_attr}]
+----
+include::{sourcedir}/_0064_MinimumPathSum_3.java[tag=answer]
+----
+--
 ====
 
 == 参考资料

docs/images/0064-01.jpg

@@ -315,6 +315,11 @@ endif::[]
 |{doc_base_url}/0980-unique-paths-iii.adoc[题解]
 |❌ 明知是回溯，但在处理当前节点时，总把当前和下一步混在一起。有思路，没写出代码。
 
+|{counter:codes2503}
+|{leetcode_base_url}/minimum-path-sum/[64. Minimum Path Sum^]
+|{doc_base_url}/0064-minimum-path-sum.adoc[题解]
+|✅ 动态规划。直接在原有矩阵上操作即可。
+
 |===
 
 截止目前，本轮练习一共完成 {codes2503} 道题。

logbook/202503.adoc

@@ -0,0 +1,26 @@
+package com.diguage.algo.leetcode;
+
+public class _0064_MinimumPathSum_3 {
+  // tag::answer[]
+  /**
+   * @author D瓜哥 · https://www.diguage.com
+   * @since 2025-04-18 21:51:48
+   */
+  public int minPathSum(int[][] grid) {
+    int row = grid.length;
+    int col = grid[0].length;
+    for (int i = 1; i < col; i++) {
+      grid[0][i] += grid[0][i - 1];
+    }
+    for (int i = 1; i < row; i++) {
+      grid[i][0] += grid[i - 1][0];
+    }
+    for (int r = 1; r < row; r++) {
+      for (int c = 1; c < col; c++) {
+        grid[r][c] += Math.min(grid[r - 1][c], grid[r][c - 1]);
+      }
+    }
+    return grid[row - 1][col - 1];
+  }
+  // end::answer[]
+}