题目链接:http://acm.split.hdu.edu.cn/showproblem.php?pid=4632 题意:求回文串子串的的个数. 思路:看转移方程就能理解了. dp[i][j] 表示区间i j 之间的回文子串的个数. 状态转移方程:dp[i][j]=dp[i][j-1]+dp[i+1][j]-dp[i+1][j-1];         if(str[i]==str[j]) dp[i][j]=dp[i][j]+dp[i+1][j-1]+1; 代码: #include<iostrea…

Problem Description In mathematics, a subsequence is a sequence that can be derived from another sequence by deleting some elements without changing the order of the remaining elements. For example, the sequence <A, B, D> is a subsequence of <A,…

题目 参考自博客:http://blog.csdn.net/u011498819/article/details/38356675 题意:查找这样的子回文字符串(未必连续,但是有从左向右的顺序)个数. 简单的区间dp,哎,以为很神奇的东西,其实也是dp,只是参数改为区间,没做过此类型的题,想不到用dp,以后就 知道了,若已经知道[0,i],推[0,i+1], 显然还要从i+1 处往回找,dp方程也简单: dp[j][i]=(dp[j+1][i]+dp[j][i-1]+10007-dp[j+1][…

题意 给定一个字符串,问有多少个回文子串(两个子串可以一样). 思路 注意到任意一个回文子序列收尾两个字符一定是相同的,于是可以区间dp,用dp[i][j]表示原字符串中[i,j]位置中出现的回文子序列的个数,有递推关系: dp[i][j]=dp[i+1][j]+dp[i][j-1]-dp[i+1][j-1]  (*) 如果i和j位置出现的字符相同,那么dp[i][j]可以由dp[i+1][j-1]中的子序列加上这两个字符构成回文子序列,也就是 dp[i][j]+=dp[i+1][j-1],注意…

题目链接 题目大意 给你几个字符串 (1<len(s)<1000) ,要你求每个字符串的回文序列个数.对于10008取模. Solution 区间DP. 比较典型的例题. 状态定义: 令 \(f[i][j]\) 表示 \(i\) 到 \(j\) 的回文序列个数,\(s\) 为给出的字符串. 状态转移: \(s[i]\neq s[j]\) 那么此时 \(f[i][j]\) 即为\(f[i][j-1]\),\(f[i+1][j]\)之和. 但由于 \(i+1->j-1\)的我们明显重复统计了…

link:http://acm.hdu.edu.cn/showproblem.php?pid=4632 refer to: o(╯□╰)o……明明百度找的题解,然后后来就找不到我看的那份了,这位哥们对不住了…… #include <iostream> #include <cstdio> #include <cstdlib> #include <cstring> #include <cmath> #include <cctype> #i…

题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=4632 题目大意:给你若干个字符串,回答每个字符串有多少个回文子序列(可以不连续的子串).解题思路: 设dp[i][j]为[i,j]的回文子序列数,那么得到状态转移方程: dp[i][j]=(dp[i+1][j]+dp[i][j-1]-dp[i+1][j-1]+MOD)%MOD if(str[i]==str[j]) dp[i][j]+=dp[i-1][j+1]+1 代码: #include<cstdi…

Palindrome subsequence Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 131072/65535 K (Java/Others)Total Submission(s): 4513    Accepted Submission(s): 1935 Problem Description In mathematics, a subsequence is a sequence that can be derived f…

Palindrome subsequence Problem Description In mathematics, a subsequence is a sequence that can be derived from another sequence by deleting some elements without changing the order of the remaining elements. For example, the sequence <A, B, D> is a…

标签(空格分隔): 区间qp Palindrome subsequence \[求一个string的 回文子序列 的个数 \] 少废话,上代码. #include<bits/stdc++.h> //头文件没有什么问题 using namespace std; //名字空间没有什么问题 const int maxn = 1000 +5; // 字符串的最大长度 const int mod = 10007;//题目规定的模数 int n,cnt;//n:有多少个字符串,cnt:记录当前有多少个ca…