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题意:添加最少的字符使之成为回文串 #include<cstdio> #include<iostream> #include<algorithm> #include<cstring> #include<cmath> #include<queue> using namespace std; ; int n,m,t; short dp[maxn][maxn]; char s[maxn]; int main() { int i,j,k; #…

题目链接:http://poj.org/problem?id=3280 思路: dp[i][j] :=第i个字符到第j个字符之间形成回文串的最小费用. dp[i][j]=min(dp[i+1][j]+cost[s[i-1]-'a'],dp[i][j-1]+cost[s[j-1]-'a']); if(s[i-1]==s[j-1]) dp[i][j]=min(dp[i+1][j-1],dp[i][j]); 注意循环顺序,我觉得这题就是这里是tricky: #include<iostream> #i…

这题的题意为,给你一个环状的字符串,有两只兔子分别从某任意的石头上开始跳跃.一只顺时针跳.一只逆时针跳.两只兔子每一次落脚处石头的质量都相同.兔子要一步一步的跳,且不能跳到之前跳到过的地方.总的来说,就是一只兔子最多就只能跳一整圈.每一次两只兔子落点的权值都相同,问兔子最多可以跳几次.这一题可以简化,用区间DP来求所有区间内的最长回文串长度.之后一遍for循环遍历,把区间[0,n-1]划分成[0,k]和[k+1,n-1].找到这两个区间回文串长度和的最大值,即为答案.证明如下: 我们把区间分成了…

A palindromic number or numeral palindrome is a 'symmetrical' number like 16461 that remains the same when its digits are reversed. In this problem you will be given two integers i j, you have to find the number of palindromic numbers between i and j…

Times:5000ms: Memory limit:262144 kB 给定字符串S(|S|<=5000),下标由1开始.然后Q个问题(Q<=1e6),对于每个问题,给定L,R,回答区间[L,R]里有多少个回文串. 请想出两种或者以上的方法. ------------------------分界线-------------------------- 方法1:区间DP.           容斥一下,dp[i][j]=dp[i][j-1]+dp[i+1][j]-dp[i+1][j-1]+ok[…

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Palindrome Time Limit: 3000MS   Memory Limit: 65536K Total Submissions: 53431   Accepted: 18454 Description A palindrome is a symmetrical string, that is, a string read identically from left to right as well as from right to left. You are to write a…

［抄题］: Given a string s, find the longest palindromic subsequence's length in s. You may assume that the maximum length of s is 1000. Example 1:Input: "bbbab" Output: 4 One possible longest palindromic subsequence is "bbbb". [暴力解法]: 时间分…

题意: 输入正整数n和k(1<=n<=400,1<=k<=10),求长度为n的01串中有多少个不含长度至少为k的回文连续子串.例如,n=k=3时只有4个串满足条件:001,011,100,110. 分析: 做这题的时候走了很多弯路,自以为想到了一个不用表示状态的dp,然而在保证不回文的时候就发现了很多问题.其实本题k的规模很小,所以应该要想到状压的.一个串中只要保证不含长度为k也不含长度为k+1的回文串,那么就不会出现大于k的回文串,所以我们构造的时候只要保证前面两个条件符合即可.…