$ g++ --version
g++ (Homebrew GCC 9.2.0) 9.2.0
Copyright (C) 2019 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ g++ --version
#include <bits/stdc++.h>
using namespace std;

int main() {
    int a;
    int b1 = 3;
    int b2 = 1;
    int b3 = 5;

    a = min({b1, b2, b3});
    cout << a << endl;

    // max と同じこと
    cout << min({b1, b2, b3}, greater<int>()) << endl;

    // int型配列の最小値
    // min_element は iterator が返却される
    int t[] = {4, 2, 5};
    cout << *min_element(t, t+3) << endl;

    // vector 型の最小値
    vector<int> v = {3, 1, 5};
    cout << *min_element(v.begin(), v.end()) << endl;
}

1
5
2
1