题目链接: https://leetcode.com/problems/count-different-palindromic-subsequences/description/ 730.Count Different Palindromic Subsequences 题意 给你一个只包含a.b.c.d字符的字符串,总共有多少个不重复的回文子序列. 题解 容易想到这题可以用动态规划的方法来解决. 1.dp[l][r][k]表示区间[l,r]内,以字符k+'a'结尾的回文子序列个数. 当k+'a'…

lc 730 Count Different Palindromic Subsequences 730 Count Different Palindromic Subsequences Given a string S, find the number of different non-empty palindromic subsequences in S, and return that number modulo 10^9 + 7. A subsequence of a string S i…

Given a string S, find the number of different non-empty palindromic subsequences in S, and return that number modulo 10^9 + 7. A subsequence of a string S is obtained by deleting 0 or more characters from S. A sequence is palindromic if it is equal…

作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 目录 题目描述 题目大意 解题方法 记忆化搜索 动态规划 日期 题目地址:https://leetcode.com/problems/count-different-palindromic-subsequences/description/ 题目描述 Given a string S, find the number of different non-empty palindromic…

Given a string S, find the number of different non-empty palindromic subsequences in S, and return that number modulo 10^9 + 7. A subsequence of a string S is obtained by deleting 0 or more characters from S. A sequence is palindromic if it is equal…

Given a string S, find the number of different non-empty palindromic subsequences in S, and return that number modulo 10^9 + 7. A subsequence of a string S is obtained by deleting 0 or more characters from S. A sequence is palindromic if it is equal…

Given a string S, find the number of different non-empty palindromic subsequences in S, and return that number modulo 10^9 + 7. A subsequence of a string S is obtained by deleting 0 or more characters from S. A sequence is palindromic if it is equal…

Given a string S, find the number of different non-empty palindromic subsequences in S, and return that number modulo 10^9 + 7. A subsequence of a string S is obtained by deleting 0 or more characters from S. A sequence is palindromic if it is equal…

Given an integer array nums, return the number of range sums that lie in [lower, upper] inclusive.Range sum S(i, j) is defined as the sum of the elements in nums between indices i and j (i ≤ j), inclusive. Note:A naive algorithm of O(n2) is trivial.…

题目大意 给定一个字符串,要求你删除尽量少的字符,使得原字符串变为最长回文串,并把回文串输出,如果答案有多种,则输出字典序最小的 题解 有两种解法,第一种是把字符串逆序,然后求两个字符串的LCS,并记录LCS,长度就等于最长回文串的长度,不过求出来的LCS不一定是回文串,例如下面这个例子 s = 1 5 2 4 3 3 2 4 5 1 reverse(s) = 1 5 4 2 3 3 4 2 5 1 LCS = 1 5 2 3 3 4 5 1 所以我们只需要LCS的前半段即可 代码: #incl…