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  • [leetcode] @python 115. Distinct Subsequences

    题目链接

    https://leetcode.com/problems/distinct-subsequences/

    题目原文

    Given a string S and a string T, count the number of distinct subsequences of T in S.

    A subsequence of a string is a new string which is formed from the original string by deleting some (can be none) of the characters without disturbing the relative positions of the remaining characters. (ie, "ACE" is a subsequence of "ABCDE" while "AEC" is not).

    Here is an example:
    S = "rabbbit", T = "rabbit"

    Return 3.

    题目大意

    给定字符串S和T,判断S中有多少个不同的子串T

    解题思路

    动态规划求解

    代码

    class Solution(object):
        def numDistinct(self, s, t):
            """
            :type s: str
            :type t: str
            :rtype: int
            """
            dp = [[0 for i in range(len(t) + 1)] for j in range(len(s) + 1)]
            for j in range(len(s) + 1):
                dp[j][0] = 1
            for i in range(1, len(s) + 1):
                for j in range(1, min(i + 1, len(t) + 1)):
                    if s[i - 1] == t[j - 1]:
                        dp[i][j] = dp[i - 1][j] + dp[i - 1][j - 1]
                    else:
                        dp[i][j] = dp[i - 1][j]
            return dp[len(s)][len(t)]      
    
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  • 原文地址:https://www.cnblogs.com/slurm/p/5287914.html
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