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