技術標籤：ios

題目連結

連結

翻譯

translation

題解

先用 \(2\) 然後用 \(1\) 補來湊n/2就行。

挺顯然的一個貪心。

程式碼

#include <bits/stdc++.h>
#define lson l,mid,rt*2
#define rson mid+1,r,rt*2+1
#define LL long long
using namespace std;

const int N = 100;

int a[N+10];

int main(){
    ios::sync_with_stdio(0),cin.tie(0);
    int T;
    cin >> T;
    while (T--){
        int n;
        cin >> n;
        int cnt[3];
        cnt[1] = cnt[2] = 0;
        for (int i = 1;i <= n; i++){
            cin >> a[i];
            cnt[a[i]]++;
        }
        int goal = cnt[1] + cnt[2]*2;
        if (goal%2==1){
            cout <<"NO"<<endl;
        }else{
            goal/=2;
            int x,y;
            //x*2+y = goal
            int t = goal;
            x = goal/2;
            x = min(x,cnt[2]);
            t-=x*2;
            if (t<=cnt[1]){
                cout <<"YES"<<endl;
                continue;
            }
            cout <<"NO"<<endl;
        }
    }
    return 0;
}