LeetCode:Minimum Path Sum

Minimum Path Sum
Editorial Solution
Total Accepted: 70466 
Total Submissions: 201784 
Difficulty: Medium
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.
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Array Dynamic Programming
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(M) Unique Paths (H) Dungeon Game
c++ code:

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