[leetcode] Minimum Path Sum

From : https://leetcode.com/problems/minimum-path-sum/
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.

class Solution {
public:
int minPathSum(vector<vector<int>>& grid) {
int m, n;
if(!(m=grid.size()) || !(n=grid[0].size())) return 0;
for(int j=1; j<n; j++) grid[0][j] += grid[0][j-1];
for(int i=1; i<m; i++) grid[i][0] += grid[i-1][0];
for(int i=1; i<m; i++) {
for(int j=1; j<n; j++) {
grid[i][j] += min(grid[i-1][j], grid[i][j-1]);
}
}
return grid[m-1][n-1];
}
};

public class Solution {
public int minPathSum(int[][] grid) {
if(grid == null || grid.length == 0) {
return 0;
}
int m = grid.length, n = grid[0].length;
for(int i=1; i<m; ++i) {
grid[i][0] += grid[i-1][0];
}
for(int j=1; j<n; ++j) {
grid[0][j] += grid[0][j-1];
}

for(int i=1; i<m; ++i) {
for(int j=1; j<n; ++j) {
if(grid[i-1][j] < grid[i][j-1]) {
grid[i][j] += grid[i-1][j];
} else {
grid[i][j] += grid[i][j-1];
}
}
}
return grid[m-1][n-1];
}
}