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.

Analyse: dp[i][j] = min(dp[i - 1][j], dp[i][j - 1]) + grid[i][j];

Runtime: 32ms.

class Solution {
public:
    int minPathSum(vector<vector<int>>& grid) {
        if(grid.size() == 0) return 0;
        int row = grid.size(); //row size
        int col = grid[0].size(); //column size
        
        vector<vector<int> > dp;
        dp = grid;
        for(int i = 1; i < row; i++) dp[i][0] = dp[i - 1][0] + grid[i][0];
        for(int j = 1; j < col; j++) dp[0][j] = dp[0][j - 1] + grid[0][j];
        
        for(int i = 1; i < row; i++){
            for(int j = 1; j < col; j++){
                dp[i][j] = min(dp[i - 1][j], dp[i][j - 1]) + grid[i][j];
            }
        }
        return dp[row - 1][col - 1];
    }
};