#pragma GCC optimize(3,"Ofast","inline")

freopen(".in","r",stdin);
freopen(".out","w",stdout);

ios::sync_with_stdio(false);

clock_t startTime = clock();//头文件ctime;

clock_t endTime = clock();
cout << "整个程序用时："  << double(endTime - startTime) / CLOCKS_PER_SEC << "s" << endl;//测代码运行时间;

二分答案模板

int l=1,r=ll;// 1 是答案的最小值，ll是答案的最大值
while(l<=r)
{
    int mid=(l+r)>>1,q=check(mid);//“>>1”相当于“/2”
    if(q>m)r=mid-1;
    else l=mid+1;
}

typedef long long ll;