LeetCode Problem : Minimum Path Sum

Problem

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.

Code

int minPathSum(vector<vector<int> > &grid) {
    // IMPORTANT: Please reset any member data you declared, as
    // the same Solution instance will be reused for each test case.
    int m = grid.size();
    int n = grid[0].size();
    vector<vector<int> > M(m,vector<int>(n,0));
    M[0][0] = grid[0][0];
    for(int i = 1;i < m;++i)
        M[i][0] = M[i - 1][0] + grid[i][0];
    for(int j = 1;j < n;++j)
        M[0][j] = M[0][j - 1] + grid[0][j];
    for(int i = 1;i < m;++i){
        for(int j = 1;j < n;++j){
            M[i][j] = min(M[i - 1][j] , M[i][j - 1]) + grid[i][j];
        }
    }
    return M[m - 1][n - 1];
}