题面在这里! (会考完之后休闲休闲2333) 可以发现,如果把一个串中"()"自动删除,最后剩的一定是形如"))))....))(((..((("这样的串,然后我们多加进去的括号的个数就是剩的这个串的长度.. 然鹅这个题首先要求的是最后总长度最小,并且我们可以观察发现把最后一个循环位移到最前面是会使一对")("相抵消的. 所以我们最后的最优答案一定是排除已经匹配的括号之后只剩一种括号的串,我们枚举一下循环位移了多少(循环位移之后一定是一个原串的后…

(CodeForces - 5C)Longest Regular Bracket Sequence time limit per test:2 seconds memory limit per test:256 megabytes input:standard input output:standard output This is yet another problem dealing with regular bracket sequences. We should remind you t…

Codeforces 3 D 题意:有一个括号序列,其中一些位置是问号,把第\(i\)个问号改成(需要\(a_i\)的代价,把它改成)需要\(b_i\)的代价. 问使得这个括号序列成立所需要的最小代价. 思路1: 这个是正统的贪心. 首先我们假设所有的位置上都是),那么我们在从左向右扫描的途中会发现一些问题. 比如:我们原来的序列是(??),现在假设成了())),那么在第三个字符处就会发现我们的打开的左括号数量为\(-1\),这是肯定不行的,所以我们必须把第二个字符或者第三个字符改成左括号以把左…

Description 给出一个括号序列,中间有一些问号,将第i个问号换成左括号代价是a[i],换成右括号代价是b[i],问如果用最少的代价将这个括号序列变成一个合法的括号序列 Input 第一行一个括号序列,假设其中有m个问号,则之后输入m行,每行两个整数a[i]和b[i]表示把第i个问号换成左括号或右括号的代价(括号序列长度不超过5e4,1<=a[i],b[i]<=1e6) Output 如果不存在一种合理的替换方案使得该序列变成一个合法的括号序列则输出-1,否则输出最小代价和替换后的合法…

E. Correct Bracket Sequence Editor time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Recently Polycarp started to develop a text editor that works only with correct bracket sequences (abbrev…

C. Replace To Make Regular Bracket Sequence 题目连接: http://www.codeforces.com/contest/612/problem/C Description You are given string s consists of opening and closing brackets of four kinds <>, {}, [], (). There are two types of brackets: opening and…

C. Longest Regular Bracket Sequence Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/problemset/problem/5/C Description This is yet another problem dealing with regular bracket sequences. We should remind you that a bracket sequence…

E. Correct Bracket Sequence Editor 题目连接: http://www.codeforces.com/contest/670/problem/E Description Recently Polycarp started to develop a text editor that works only with correct bracket sequences (abbreviated as CBS). Note that a bracket sequence…

D. Least Cost Bracket Sequence 题目连接: http://www.codeforces.com/contest/3/problem/D Description This is yet another problem on regular bracket sequences. A bracket sequence is called regular, if by inserting "+" and "1" into it we get a…

题目传送门 /* 题意:求最长括号匹配的长度和它的个数 贪心+stack:用栈存放最近的左括号的位置,若是有右括号匹配,则记录它们的长度,更新最大值,可以在O (n)解决 详细解释:http://blog.csdn.net/taoxin52/article/details/26012167 */ #include <cstdio> #include <algorithm> #include <cstring> #include <cmath> #includ…