d64_q1a_second_min.cpp ​

#include <algorithm>
#include <iostream>
#include <list>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <vector>
using namespace std;

int get_second_min(stack<int> &s) {
    std::stack<int> another;
    std::vector<int> c;

    while (!s.empty()) {
        another.push(s.top());
        c.push_back(s.top());
        s.pop();
    }

    std::sort(c.begin(), c.end());

    auto it = c.cbegin();
    int min = *it;

    while (*(++it) == min) {
    }

    int answer = *it;

    while (!another.empty()) {
        s.push(another.top());
        another.pop();
    }

    return answer;
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    int n;
    cin >> n;
    vector<int> v(n);
    for (int i = 0; i < n; i++) {
        cin >> v[i];
    }
    // repeat n-1 times
    for (int last = 1; last < n; last += 1) {
        stack<int> s;
        // build s;
        bool distinct = false;
        for (int i = last; i >= 0; i--) {
            s.push(v[i]);
            if (v[i] != v[0]) distinct = true;
        }
        cout << "--use v[" << last << "] to v[0] --"
             << "\n";
        if (distinct) {
            // call get_second_min if we have at least 2 distinct value
            int answer = get_second_min(s);
            // print result and s
            cout << "result is " << answer << "\n";
            cout << "size of s is " << s.size() << "\n"
                 << "member of s are ";
            while (s.size() > 0) {
                cout << s.top() << " ";
                s.pop();
            }
            cout << "\n";
        } else {
            cout << "skip because s has only one value\n\n\n";
        }
    }
    return 0;
}