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  • [leetcode]Unique Paths @ Python

    原题地址:https://oj.leetcode.com/problems/unique-paths/

    题意:

    A robot is located at the top-left corner of a m x n grid (marked 'Start' in the diagram below).

    The robot can only move either down or right at any point in time. The robot is trying to reach the bottom-right corner of the grid (marked 'Finish' in the diagram below).

    How many possible unique paths are there?

    Above is a 3 x 7 grid. How many possible unique paths are there?

    Note: m and n will be at most 100.

    解题思路:这道题和climbing stairs很像,可以用动态规划解决。状态转移方程为dp[i][j]=dp[i-1][j]+dp[i][j-1]。

    代码:

    class Solution:
        # @return an integer
        def uniquePaths(self, m, n):
            if m == 1 and n == 1:
                list = [[1]]
            elif m == 1 and n > 1:
                list = [[1 for i in range(n)]]
            elif m > 1 and n == 1:
                list = [[1] for i in range(m)]
            else:
                list = [[0 for i in range(n)] for i in range(m)]
                for i in range(0, n):
                    list[0][i] = 1
                for i in range(0, m):
                    list[i][0] = 1
                for i in range(1, m):
                    for j in range(1, n):
                        list[i][j] = list[i-1][j] + list[i][j-1]
            return list[m-1][n-1]
                
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  • 原文地址:https://www.cnblogs.com/zuoyuan/p/3785221.html
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