模拟退火2 P3878 [TJOI2010]分金币

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
ll ans,n,sum;
int a[100];

int f()
{
    int t=0;
    for(int i=1;i<=n/2;i++)t+=a[i];
    return abs(sum-2*t);
}
void mnth()
{
    for(double T=5000;T>1e-15;T*=0.945)
    {
        int x1=rand()%n+1;
        int x2=rand()%n+1;
        swap(a[x1],a[x2]);
        int nowsum=f();
        double del=nowsum-ans;
        if(del<0)ans=nowsum;
        else if(exp((-del)/T)*RAND_MAX<rand())swap(a[x1],a[x2]);
    }
}
int main()
{
    ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
    int T;
    cin>>T;
    while(T--)
    {
        ans=INT_MAX,sum=0;
        cin>>n;
        for(int i=1;i<=n;i++)cin>>a[i],sum+=a[i];
        int x=1000;
        while(x--)mnth();
        cout<<ans<<endl;
    }
    return 0;
}