20171108 模拟题 T1

#include<iostream>
#include<cstring>
#include<cstdio>
#include<algorithm>

using namespace std;
const int N = 100000 + 10;
char s[N];
int ans,ans1,ans2;
int pre[N],nxt[N];
int main(){
    //freopen("shower.in","r",stdin);
    //freopen("shower.out","w",stdout);
    scanf("%s",s + 1);
    int len = strlen(s + 1);
    for(int i = 1;i <= len;++ i){
        pre[i] = i - 1;
        nxt[i - 1] = i;
    }
    nxt[len] = len + 1;
    pre[len + 1] = len;
    if(s[1] != ‘(‘) ans ++;
    if(s[len] != ‘)‘) ans ++;
    s[1] = ‘(‘,s[len] = ‘)‘;
    for(int i = 1;i < len;i = nxt[i]){
        if(pre[i] == 0 && s[i] == ‘)‘){
            ans ++;
            s[i] = ‘(‘;
        } 
        if(nxt[i] == len + 1 && s[i] == ‘(‘){
            ans ++;
            s[i] = ‘)‘;
        }
        if(s[nxt[i]] == ‘)‘ && s[i] == ‘(‘){
            nxt[pre[i]] = nxt[nxt[i]];
            pre[nxt[nxt[i]]] = pre[i];
        }
        if(s[pre[i]] == ‘(‘ && s[i] == ‘)‘){
            nxt[pre[pre[i]]] = nxt[i];
            pre[nxt[i]] = pre[pre[i]];
        }
    }
    int sum = 0;
    for(int i = 0;i < len + 1;i = nxt[i]){
        if(s[nxt[i]] == ‘(‘){
             sum ++;
        }
    }
    cout << ans + (sum / 2) << ‘\n‘;
    return 0;
}