64. Minimum Path Sum

Given 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.

public class Solution {
    public int minPathSum(int[][] grid) {
        if(grid == null)
            return 0;
        int dp[][] = new int[grid.length][grid[0].length];
        dp[0][0] = grid[0][0];
        for(int i = 0; i < grid.length ; i++){
            for(int j = 0; j < grid[0].length ; j++){
                if(i > 0 && j > 0)
                    dp[i][j] = grid[i][j] + Math.min(dp[i-1][j], dp[i][j-1]);
                else if(i > 0 && j == 0)
                     dp[i][j] = grid[i][j] + dp[i-1][j];
                else if(i == 0 && j > 0)
                     dp[i][j] = grid[i][j] + dp[i][j-1];
            }
        }
        return dp[grid.length -1][grid[0].length-1];
    }
}