LeetCode 64.最小路径和(动态规划)

题目描述

给定一个包含非负整数的 m x n 网格，请找出一条从左上角到右下角的路径，使得路径上的数字总和为最小。

说明：每次只能向下或者向右移动一步。

示例:

输入:
[
[1,3,1],
[1,5,1],
[4,2,1]
]
输出: 7
解释: 因为路径 1→3→1→1→1 的总和最小。

思路

详见链接

代码

class Solution():
	def minPathSum(self,grid:[[int]]) ->int:
		m = len(grid)
		n = len(grid[0])
		for i in range(0,m):
			for j in range(0,n):
				if i == j == 0:
					continue
				elif i == 0:   
					grid[i][j] = grid[i][j-1] + grid[i][j]
				elif j == 0:  
					grid[i][j] = grid[i-1][j] + grid[i][j]
				else:
					grid[i][j] = min(grid[i][j-1],grid[i-1][j]) + grid[i][j]
		return grid[-1][-1]
test = Solution()
test.minPathSum([
  [1,3,1],
  [1,5,1],
  [4,2,1]
])

效果