from left-top to right-bottom
public class Solution {
public int minPathSum(int[][] grid) {
int m = grid.length;
int n = grid[0].length;
int dp[][] = new int[m][n];
dp[0][0] = grid[0][0];
for (int i=1; i<m; i++)
dp[i][0] = dp[i-1][0] + grid[i][0];
for (int j=1; j<n; j++)
dp[0][j] = dp[0][j-1] + grid[0][j];
for (int i=1; i<m; i++) {
for (int j=1; j<n; j++) {
dp[i][j] = Math.min(dp[i-1][j], dp[i][j-1]) + grid[i][j];
}
}
return dp[m-1][n-1];
}
}
