1400*B. Applejack and Storages（贪心&字符串）

Problem - 1393B - Codeforces

#include
using namespace std;
const int N=1e5+5;
int n,a[N],k,cnt2,cnt4;
map<int,int>mp;
int f(string str){
	int sum=0;
	for(int i=0;isize();i++) sum=sum*10+(str[i]-'0');
	return sum;
} 
signed main(){
	scanf("%d",&n);
	for(int i=1;i<=n;i++){
		int x;
		scanf("%d",&x);
		mp[x]++;
		if(mp[x]%4==0) cnt4++;
		if(mp[x]%2==0) cnt2++;
	}
	scanf("%d",&k);
	cin.get();
	while(k--){
		string s;
		getline(cin,s);
		int x=f(s.substr(2,s.size()-2));
		if(s[0]=='+'){
			mp[x]++;
			if(mp[x]%2==0) cnt2++;
			if(mp[x]%4==0) cnt4++;
		}
		else{
			mp[x]--;
			if(mp[x]%2==1) cnt2--;
			if(mp[x]%4==3) cnt4--;
		}
		if(cnt4>0&&cnt2>=4) puts("YES");
		else puts("NO");
	}
	return 0;
}