UVA - 11404 Palindromic Subsequence 题意:一个字符串,删去0个或多个字符,输出字典序最小且最长的回文字符串 不要求路径区间DP都可以做 然而要字典序最小 倒过来求LCS,转移同时维护f[i][j].s为当前状态字典序最小最优解 f[n][n].s的前半部分一定是回文串的前半部分(想想就行了) 当s的长度为奇时要多输出一个(因为这样长度+1,并且字典序保证最小(如axyzb  bzyxa,就是axb|||不全是回文串的原因是后半部分的字典序回文串可能不是最小,多…

题目传送门 题意:求LPS (Longest Palidromic Subsequence) 最长回文子序列.和回文串不同,子序列是可以不连续的. 分析:1. 推荐->还有一种写法是用了LCS的思想,dp[i][j]表示i到j的最长回文串长度,状态转移方程: 1. dp[j][j+i-1] = dp[j+1][j+i-2] + 2; (str[j] == str[j+i-1]) 2. dp[j][j+i-1] = max (dp[j+1][j+i-1], dp[j][j+i-2]); (str[…

Palindromic Subsequence Time Limit: 3000ms Memory Limit: 131072KB This problem will be judged on UVA. Original ID: 1140464-bit integer IO format: %lld      Java class name: Main   A Subsequence is a sequence obtained by deleting zero or more characte…

题意:给定一个字符串,问删除一些字符,使得它成为一个最长回访串,如果有多个,输出字典序最小的那个. 析: 我们可以把原字符串反转,然后求两个串的LCS,就得到最长回文串,不过要注意一些细节. 代码如下: #pragma comment(linker, "/STACK:1024000000,1024000000") #include <cstdio> #include <string> #include <cstdlib> #include <c…

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Problem C: Longest Common Subsequence Sequence 1: Sequence 2: Given two sequences of characters, print the length of the longest common subsequence of both sequences. For example, the longest common subsequence of the following two sequences: abcdgh…

http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=465&page=show_problem&problem=2399 最长的很简单,将串翻转过来后求两个串的lcs就是答案.. 主要是字典序那里... 还是开string来比较吧.. 注意最后输出方案时用前半段推出后半段.(因为可能lcs时会重合...) #include <cstdio> #include…

题目链接 题意:给N,第二行是答案,n个数c1---cn, 代表第一个的顺序是c1,第二个数顺序是c2; 下面每一行是学生的答案,格式同上. 注意:这个给的顺序需要处理一下,不能直接用. 思路:LCS. #include <iostream> #include <cstdio> #include <cstring> #include <cstdlib> #include <algorithm> using namespace std; #defi…

UVA 11404 - Palindromic Subsequence 求给定字符串的最长回文子序列,长度一样的输出字典序最小的. 对于 [l, r] 区间的最长回文串.他可能是[l+1, r] 和[l, r-1]两个区间的结果. 或者当s[l] == s[r]时,区间[l+1, r-1]的结果再加上以s[l], s[r]为首尾的子序列. dp[l][r] = ans(dp[l][r-1], dp[l+1][r], s[l] + dp[l+1][r-1] + s[r])  dp存的是子序列,即一…

 Palindromic Subsequence Time Limit:3000MS     Memory Limit:0KB     64bit IO Format:%lld & %llu Submit Status Practice UVA 11404 #include <stdio.h> #include <string.h> #include <algorithm> #include <string> #include <iostrea…