LeetCode_Minimum Path Sum

iven 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) {
// Start typing your C/C++ solution below
// DO NOT write int main() function
int m = grid.size();
int n = grid[0].size();

for(int i = 1; i< n ; i++)
grid[0][i] += grid[0][i-1];
for(int j = 1; j < m; j++)
grid[j][0] += grid[j-1][0];

for( int i = 1; i < m ; i++)
for( int j = 1; j < n ; j++)
{
int temp = grid[i-1][j] < grid[i][j-1] ? grid[i-1][j] : grid[i][j-1];
grid[i][j] +=temp;
}

return grid[m-1][n-1];
}
};