[leetcode]64. Minimum Path Sum(Java)

https://leetcode.com/problems/minimum-path-sum/#/description

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.

Note: You can only move either down or right at any point in time.

package go.jacob.day628;public class Demo2 {/* * 除去第一行第一列，每一格的最短路径为左一格最短路径加上当前值，或者上一格最短路径加上当前值 * Runtime: 3 ms.Your runtime beats 86.66 % of java submissions */public int minPathSum(int[][] grid) {if (grid == null || grid.length == 0 || grid[0].length == 0)return 0;int m = grid.length;int n = grid[0].length;for (int i = 1; i < m; i++) {grid[i][0] = grid[i - 1][0] + grid[i][0];}for (int i = 1; i < n; i++) {grid[0][i] = grid[0][i] + grid[0][i - 1];}for (int i = 1; i < m; i++) {for (int j = 1; j < n; j++) {grid[i][j] = (grid[i - 1][j] < grid[i][j - 1] ? grid[i - 1][j] : grid[i][j - 1]) + grid[i][j];}}return grid[m - 1][n - 1];}}