Description Sereja has a bracket sequence s1, s2, ..., sn, or, in other words, a string s of length n, consisting of characters "(" and ")". Sereja needs to answer m queries, each of them is described by two integers li, ri(1 ≤ li ≤ ri…

题目链接:http://poj.org/problem?id=2955 这题要求求出一段括号序列的最大括号匹配数量 规则如下: the empty sequence is a regular brackets sequence, if s is a regular brackets sequence, then (s) and [s] are regular brackets sequences, and if a and b are regular brackets sequences, th…

题目链接:http://poj.org/problem?id=2955 题目大意:给你一串字符串,求最大的括号匹配数. 解题思路: 设dp[i][j]是[i,j]的最大括号匹配对数. 则得到状态转移方程: if(str[i]=='('&&str[j]==')'||(str[i]=='['&&str[j]==']')){ dp[i][j]=dp[i+1][j-1]+1; }dp[i][j]=min(dp[i][j],dp[i][k]+dp[k+1][j]) ,(i<=k…

题意:最多有多少括号匹配 思路:区间dp,模板dp,区间合并. 对于a[j]来说: 刚開始的时候,转移方程为dp[i][j]=max(dp[i][j-1],dp[i][k-1]+dp[k][j-1]+2), a[k]与a[j] 匹配,结果一组数据出错 ([]]) 检查的时候发现dp[2][3]==2,对,dp[2][4]=4,错了,简单模拟了一下发现,dp[2][4]=dp[2][1]+dp[2][3]+2==4,错了 此时2与4已经匹配,2与3已经无法再匹配. 故转移方程改为dp[i][j]=…

Brackets We give the following inductive definition of a “regular brackets” sequence: the empty sequence is a regular brackets sequence, if s is a regular brackets sequence, then (s) and [s] are regular brackets sequences, and if a and b are regular…

Description We give the following inductive definition of a “regular brackets” sequence: the empty sequence is a regular brackets sequence, if s is a regular brackets sequence, then (s) and [s] are regular brackets sequences, and if a and b are regul…

Description ]. Output For each test case, print how many places there are, into which you insert a '(' or ')', can change the sequence to a regular brackets sequence. What's more, you can assume there has at least one such place. Sample Input 4 ) ())…

Sereja has a bracket sequence s1, s2, ..., sn, or, in other words, a string s of length n, consisting of characters "(" and ")". Sereja needs to answer m queries, each of them is described by two integers li, ri(1 ≤ li ≤ ri ≤ n). The a…

题目链接:http://poj.org/problem?id=1141 题目大意:给你一串字符串,让你补全括号,要求补得括号最少,并输出补全后的结果. 解题思路: 开始想的是利用相邻子区间,即dp[i+1][j]之类的方法求,像是求回文串的区间DP一样.然后花了3个多小时,GG... 错误数据: (())(]][[)my:6 (()()()[][][][])ans:4 (())([][][][])括号匹配跟回文串不同,并不能通过dp[i+1][j]或者dp[i][j-1]推得dp[i][j],可…

C. Sereja and Brackets time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Sereja has a bracket sequence s1, s2, ..., sn, or, in other words, a string s of length n, consisting of characters "(…