제출 #967988

#제출 시각아이디문제언어결과실행 시간메모리
967988Darren0724Line Town (CCO23_day1problem3)C++17
0 / 25
1 ms604 KiB
#include <bits/stdc++.h>
using namespace std;
#define all(x) x.begin(),x.end()
#define ll long long 
#define LCBorz ios_base::sync_with_stdio(false);cin.tie(0);
const int N=1000005;
const int mod=1e6+3;
const int INF=1e9;
int32_t main(){
    LCBorz;
    int n;cin>>n;
    vector<int> v(n+2),pre(n+2),suf(n+2);
    for(int i=1;i<=n;i++){
        cin>>v[i];
        assert(abs(v[i])==1);
    }
    int last=0,cnt=0,can=1;
    for(int i=1;i<=n;i++){
        if(v[i]==-1){
            if(last)can=0;
        }
        else{
            cnt++;
            last^=1;
        }
        if(can&&last==0){
            pre[i]=cnt/2;
        }
        else{
            pre[i]=INF;
        }
    }
    last=0,can=1,cnt=0;
    for(int i=n;i>=1;i--){
        if(v[i]==1){
            if(last)can=0;
        }
        else{
            cnt++;
            last^=1;
        }
        if(can&&last==0){
            suf[i]=cnt/2;
        }
        else{
            suf[i]=INF;
        }
    }
    int ans=INF;
    for(int i=0;i<=n;i++){
        ans=min(ans,pre[i]+suf[i+1]);
    }
    if(ans==INF){
        cout<<-1<<endl;
    }
    else{
        cout<<ans<<endl;
    }
    
    return 0;
}
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