[Codeforces] Educational42 Merge Equals

題目連結：http://codeforces.com/contest/962/problem/D
　　用map亂做。
　　好感嘆我當時竟然寫得出來......。

#include<bits/stdc++.h>
#define int long long
using namespace std;
map<int,priority_queue<int,vector<int>,greater<int> > > m,ss;
int n;
vector<pair<int,int> > s;
signed main()
{
    cin >> n;
    for(int i = 0; i < n; i++)
    {
        int a; cin >> a;
        m[a].push(i);
    }
    for(auto i:m)
    {
        //cout << i.first << endl;
        while(i.second.size())
        {
            if(i.second.size() == 1)
            {
                ss[i.first].push(i.second.top());
                break;  
            }
            //cout << i.second.top() << " ";
            i.second.pop();
            int p = i.second.top(); i.second.pop(); //cout << p << endl;
            m[i.first*2].push(p);
        }
    }
    s.clear();
    for(auto i:ss)
    {
        if(i.second.size()) 
        {
            s.push_back({i.second.top(),i.first});
            //cout << i.second.top() << " " << i.first << endl;
        }
    }
    sort(s.begin(),s.end());
    cout << s.size() << endl;
    for(auto i:s) cout << i.second << " "; cout << endl;
}