leetcode 64

https://leetcode.com/problems/minimum-path-sum/description/

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.

我用了三种是实现方式，在原来数组上计算是效率最高的，但这里有一个技巧，上就是从1，1开始计算，这样循环判断少一些。这个思路是排名第一的程序

/** * @param {number[][]} grid * @return {number} */var minPathSum = function(grid) {    //dianx xianx daishu    n=grid.length;    m=grid[0].length;    var arr=[];    var result =0;    if(n==1){        for(i=0;i<m;i++){            result+=grid[0][i];        }        return result;    }    for(i=0;i<n;i++){        arr[i]=[];        for(j=0;j<m;j++){            if(i==0 && j==0){                arr[i][j]=grid[i][j];                continue;            }            if(i==0){                arr[i][j]=arr[i][j-1]+grid[i][j];                continue;            }            if(j==0){                arr[i][j]=arr[i-1][j]+grid[i][j];                continue;            }            arr[i][j]=Math.min(arr[i][j-1],arr[i-1][j])+grid[i][j];        }    }    return arr[n-1][m-1];    function search(i,j){        if(i==0 && j==0){            return grid[i][j];        }        if(i==0){            result=0;            for(p=0;p<=j;p++)                result+=grid[0][p];            return result;        }        if(j==0){            result=0;            for(p=0;p<=i;p++)                result+=grid[p][j];            return result;        }        if(i != 0 && j!=0){            return Math.min(search(i-1,j)+grid[i][j],search(i,j-1)+grid[i][j]);        }    }    return search(n-1,m-1);};var minPathSum1 = function(grid) {    n=grid.length;    m=grid[0].length;    for(i=0;i<n;i++){        for(j=0;j<m;j++){            if(i==0 && j==0){                continue;            }            if(i==0){                grid[i][j]+=grid[i][j-1];                continue;            }            if(j==0){                grid[i][j]+=grid[i-1][j];                continue;            }            if(i!=0 && j!=0){                grid[i][j]+=grid[i][j-1]>grid[i-1][j]?grid[i-1][j]:grid[i][j-1];            }        }    }    return grid[n-1][m-1];}//console.log(minPathSum([[0]]));//console.log(minPathSum([[1,2],[1,1]]));console.log(minPathSum1([[1,2],[1,1]]));