CodeForces 990C
Description
A bracket sequence is a string containing only characters "(" and ")".
A regular bracket sequence is a bracket sequence that can be transformed into a correct arithmetic expression by inserting characters "1" and "+" between the original characters of the sequence. For example, bracket sequences "()()", "(())" are regular (the resulting expressions are: "(1)+(1)", "((1+1)+1)"), and ")(" and "(" are not.
You are given nn bracket sequences s1,s2,…,sns1,s2,…,sn. Calculate the number of pairs i,j(1≤i,j≤n)i,j(1≤i,j≤n) such that the bracket sequence si+sjsi+sj is a regular bracket sequence. Operation ++ means concatenation i.e. "()(" + ")()" = "()()()".
If si+sjsi+sj and sj+sisj+si are regular bracket sequences and i≠ji≠j, then both pairs (i,j)(i,j) and (j,i)(j,i) must be counted in the answer. Also, if si+sisi+si is a regular bracket sequence, the pair (i,i)(i,i) must be counted in the answer.
Input
The first line contains one integer n(1≤n≤3⋅105)n(1≤n≤3⋅105) — the number of bracket sequences. The following nn lines contain bracket sequences — non-empty strings consisting only of characters "(" and ")". The sum of lengths of all bracket sequences does not exceed 3⋅1053⋅105.
Output
In the single line print a single integer — the number of pairs i,j(1≤i,j≤n)i,j(1≤i,j≤n) such that the bracket sequence si+sjsi+sj is a regular bracket sequence.
Sample Input
3
)
()
(
2
2
()
()
4
Hint
In the first example, suitable pairs are (3,1)(3,1) and (2,2)(2,2).
In the second example, any pair is suitable, namely (1,1),(1,2),(2,1),(2,2)(1,1),(1,2),(2,1),(2,2).
括号匹配问题,需要注意几个细节。
有以下几种情况是不能与其他组括号构成合法的括号:)( )((( )))(
已经是合法的括号组不需要与不合法的括号组匹配。
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<algorithm>
#include<queue>
#include<stack>
#include<deque>
#include<map>
#include<iostream>
using namespace std;
typedef long long LL;
const double pi=acos(-1.0);
const double e=exp();
const int N = ; #define lson i << 1,l,m
#define rson i << 1 | 1,m + 1,r map<LL,LL> mp;
char con[N];
int main()
{
LL i,p,j,n,check;
LL cont=,ans=,len1,len2;
scanf("%lld",&n);
getchar();
for(j=;j<=n;j++)
{
p=check=;
len1=len2=;
memset(con,,sizeof());
scanf("%s",con);
for(i=;i<;i++)
{
if(con[i]==)
break;
if(con[i]=='(')
{
len1++;
p++;
}
else
{
p--;
if(len1)
len1--;
else
len2++;
}
}
if(len1==&&len2==)
cont++;
else
{
if(len1==)
mp[p]++;
if(len2==)
mp[p]++;
}
}
ans=cont*cont; map<LL,LL>::iterator it1;
for(it1=mp.begin();it1!=mp.end();it1++)
{
if(it1->first>)
break;
if(mp[-(it1->first)]>)
ans+=(it1->second)*mp[-(it1->first)];
}
printf("%lld\n",ans);
return ;
}
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