alt

class Solution:
    def minPathSum(self , matrix ):
        m= len(matrix)# 行
        n=len(matrix[0])# 列
        dp = [[1 for col in range(n)] for row in range(m)]
        for i in range(0,m):# 行
            for j in range(0,n):# 列
                if i==0 and j==0:
                     dp[i][j]=matrix[0][0]
                if i==0 and j!=0:
                     dp[i][j]=dp[i][j-1]+matrix[i][j]
                if i!=0 and j==0:
                      dp[i][j]=dp[i-1][j]+matrix[i][j]
                if  i!=0 and j!=0:
                    dp[i][j]=min(dp[i-1][j],dp[i][j-1])+matrix[i][j]
        return dp[m-1][n-1]