Minimum Path Sum

主要是细节和把握一位数组的能力

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