Minimum Path Sum

Given a m x n grid filled with non-negative numbers, find a path from top left to bottom right whichminimizes the sum of all numbers along its path.

Note: You can only move either down or right at any point in time.


public class Solution {
    public int minPathSum(int[][] grid) {
        //revise grid: save space 
        int m = grid.length; 
        int n = grid[0].length; 
        for (int i = 0; i < m; i++) {
            for (int j = 0; j < n; j++) {
                if (i == 0 && j != 0) grid[i][j] += grid[i][j-1]; 
                if (i != 0 && j == 0) grid[i][j] += grid[i-1][j];
                if (i != 0 && j != 0) grid[i][j] += Math.min(grid[i-1][j], grid[i][j-1]);
            }
        }
        return grid[m-1][n-1];
    }
}
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