百度之星2018初赛Bt4 P1m2（二分答案）

#include<bits/stdc++.h>
using namespace std;
#define per(i,a,b) for(int i=a;i <= b;i++)
#define Max(a,b) a=max(a,b)
#define Min(a,b) a=min(a,b)
#define Sz(x) (int)x.size()
typedef long long ll;
ll gcd(ll a,ll b){while(b){ll t=b;b=a%b;a=t;}return a;}
const int inf=0x3f3f3f3f;
const int mod=1000000007;
#define siz 300005
int n,num[siz];
bool check(int x)
{
    ll a=0,b=0;
    per(i,1,n){
        if(num[i]>x){a+=(num[i]-x)/2;}
        else b+=x-num[i];
    }
    return a>=b;
}

int main()
{
    int T;
    scanf("%d",&T);
    while(T--){
        scanf("%d",&n);
        per(i,1,n)scanf("%d",&num[i]);
        int l=0,r=1e8+2,mid,ans=0;
        while(l<=r){
            mid=(l+r)>>1;
            if(check(mid)==true){ans=mid;l=mid+1;}
            else r=mid-1;
        }
        printf("%d\n",ans);
    }

    return 0;
}