Three-point template (update)

Retrieved from the Internet:  https://www.cnblogs.com/lukelmouse/p/12545973.html

Today, my friend hit the pancake pot in Nanjing.

For integers, change midl and midr, and then re-assign +-1 to remove them.

Integer thirds template

int l = 1,r = 100;
while(l < r) {
    int lmid = l + (r - l) / 3;
    int rmid = r - (r - l) / 3;
    lans = f(lmid),rans = f(rmid);
    // 求凹函数的极小值
    if(lans <= rans) r = rmid - 1;
    else l = lmid + 1;
    // 求凸函数的极大值
    if(lasn >= rans) l = lmid + 1;
    else r = rmid - 1;
}
// 求凹函数的极小值
cout << min(lans,rans) << endl;
// 求凸函数的极大值
cout << max(lans,rans) << endl;

Floating point three-point template

const double EPS = 1e-9;
while(r - l < EPS) {
    double lmid = l + (r - l) / 3;
    double rmid = r - (r - l) / 3;
    lans = f(lmid),rans = f(rmid);
    // 求凹函数的极小值
    if(lans <= rans) r = rmid;
    else l = lmid;
    // 求凸函数的极大值
    if(lans >= rans) l = lmid;
    else r = rmid;
}
// 输出 l 或 r 都可
cout << l << endl;