原题链接

题解

很有意思的思想，一遇到括号就倒过来

code

#include<bits/stdc++.h>
#define ll long long
#define lb long double
#define lowbit(x) ((x)&(-x))
using namespace std;
const ll inf=1e18;
const ll mod=1e9+7;
const ll N=4e5;
ll qpow(ll a,ll n)
{
    ll res=1;
    while(n)
    {
        if(n&1) res=res*a%mod;
        a=a*a%mod;
        n>>=1;
    }
    return res;
}
ll inv(ll x)
{
    return qpow(x,mod-2);
}
ll fa[2000005];
ll finds(ll now){return now==fa[now]?now:finds(fa[now]);}

vector<ll> G[200005];

ll dfn[200005],low[200005];
ll cnt=0,num=0;
ll in_st[200005]={0};
stack<ll> st;
ll belong[200005]={0};

void scc(ll now,ll fa)
{
    dfn[now]=++cnt;
    low[now]=dfn[now];
    in_st[now]=1;
    st.push(now);

    for(auto next:G[now])
    {
        if(next==fa) continue;

        if(!dfn[next])
        {
            scc(next,now);
            low[now]=min(low[now],low[next]);
        }
        else if(in_st[next])
        {
            low[now]=min(low[now],dfn[next]);
        }
    }

    if(low[now]==dfn[now])
    {
        ll x;
        num++;
        do
        {
            x=st.top();
            st.pop();
            in_st[x]=0;
            belong[x]=num;
        }while(x!=now);
    }
}

int trans[500005];
void solve()
{
    string s;
    cin>>s;
    int n=s.size();

    stack<int> st;
    for(int i=0;i<n;i++)
    {
        if(s[i]=='(') st.push(i);
        else if(s[i]==')')
        {
            int last=st.top();
            st.pop();

            trans[last]=i;
            trans[i]=last;
        }
    }

    int step=1,sum=0,tem=0,id=0;
    while(tem<n)
    {
        if(s[id]=='('||s[id]==')')
        {
            id=trans[id];
            step=-step;
            sum++;
        }
        else
        {
            if(sum%2==0)
            {
                cout<<s[id];
            }
            else
            {
                if(s[id]>='a'&&s[id]<='z') cout<<(char)(s[id]-'a'+'A');
                else cout<<(char)(s[id]-'A'+'a');
            }
        }

        id+=step;
        tem++;
    }
}
int main()
{
    ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
    int TT=1;
    //cin>>TT;
    while(TT--) solve();
    return 0;
}