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