二分相关常用

自用板子

```
//排位赛3//  https://www.luogu.com.cn/problem/P7333  //
//捉摸不透的二分//
int ef(int x, int i)
{
    int l = 1, r = n;
    while (l < r)
    {
        int mid = (l + r) >> 1;
        if (max(query(i - mid, i - 1), query(i + 1, i + mid)) >= x)r = mid;
        else l = mid + 1;
    }
    return l == n ? -1 : l;
}


//整数二分板子//
while (l < r)
    {
        LL mid = (l + r + 1) >> 1;
        if (check(mid))l = mid;
        else r = mid - 1;
    }
    
//实数二分板子//
int tmp = 100;
    while (tmp--)
    {
        double mid = (l + r)/2;
        if (check(mid))l = mid;
        else r = mid;
    }
    
//实数三分板子//
double l = 0, r = 100;
       	double mid, mm;
    while (r - l > 1e-6)//一般至少要比题目要求精度小1e2//
    {
        mid = (l + r) / 2;
        mm = (mid + r) / 2;
        if (f(mid, y) < f(mm, y)) r = mm;
        else l = mid;
    }
    x = f(l, y);
```