leetcode 64. 最小路径和

思路

 

 

思路：

遍历矩阵，第一行上面：前后相加。第一列上面：上下相加。中间：比较上下后加上当前值。

代码

class Solution {
public:
    int minPathSum(vector<vector<int>>& grid) {
        for(int i = 0;i<grid.size();i++)
        {
            for(int j = 0;j<grid[0].size();j++)
            {
                if(i==0&&j == 0)
                {
                    continue;
                }
                else if(i == 0)
                {
                    grid[i][j] = grid[i][j] + grid[i][j-1];
                }
                else if(j == 0)
                {
                    grid[i][j] = grid[i][j]+grid[i-1][j];
                }
                else
                {
                grid[i][j] = min(grid[i][j-1],grid[i-1][j])+grid[i][j]; //动态规划 从上往下计算
                }

            }
        }
        return grid[grid.size()-1][grid[0].size()-1];
    }
};