64. Minimum Path Sum（js）

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.

Example:

Input:
[
  [1,3,1],
  [1,5,1],
  [4,2,1]
]
Output: 7
Explanation: Because the path 1→3→1→1→1 minimizes the sum.
题意：给一个二维数组，从左上至右下，求出经过项的和最小
代码如下：

/**
 * @param {number[][]} grid
 * @return {number}
 */
//让每项和它的左边和上边比较
var minPathSum = function(grid) {
    var rowLen=grid.length;
    var colLen=grid[0].length;
    var res=[];
    for(var i=0;i<rowLen;i++){
        res[i]=new Array();
        for(var j=0;j<colLen;j++){
            res[i][j]=0;
        }
    }
    res[0][0]=grid[0][0];
    //第一行
    for(var i=1;i<colLen;i++){
        res[0][i]=res[0][i-1]+grid[0][i];
    }
    //第一列
    for(var i=1;i<rowLen;i++){
        res[i][0]=res[i-1][0]+grid[i][0];
    }
    //其他
    for(var i=1;i<rowLen;i++){
        for(var j=1;j<colLen;j++){
            res[i][j]=grid[i][j]+Math.min(res[i][j-1],res[i-1][j]);
        }
    }
    return res[i-1][j-1];
};