PAT Practice 1

#include <bits/stdc++.h>
using namespace std;

int main () {
    int a, b;
    cin >> a >> b;
    a += b;
    stack<int> s;
    bool flag = 0;
    while(abs(a) > 999) {
        s.push(abs(a) % 1000);
        a /= 1000;
        flag = 1;
    }   
    cout << a;
    if(flag) {
        cout << ",";
    }
    int cap = s.size();
    for(int i = 0; i < cap; ++i) {
        // cout << i << " 88888" << s.top() << endl;

        if(s.top() < 10) {
            cout << "00";
        }
        else if(s.top() < 100) {
            cout << "0";
        }
        cout << s.top();

        if(i != cap - 1) {
            cout << ',';
        } 
        s.pop();
    }
    cout << endl;
    return 0;
}

#include <bits/stdc++.h>
using namespace std;
int main () {
    map<int, double, greater<int>> mp;
    int a, b;
    int num = 0;
    cin >> a;
    while(a--) {
        int s; double d;
        cin >> s >> d;
        mp[s] += d;
    }
    cin >> b;
    while(b--) {
        int s; double d;
        cin >> s >> d;
        mp[s] += d;
    }
    map<int, double, greater<int>> :: iterator it = mp.begin();
    for(it = mp.begin(); it != mp.end(); it++) {
        if(it->second != 0) {
            num++;
        }
    }

    cout << num;
    // map<int, double, greater<int>> :: iterator it = mp.begin();
    for(it = mp.begin(); it != mp.end(); it++) {
        if(it->second != 0) {
            printf(" %d %.1f", it->first, it->second);
        }
    }
    cout << endl;
}