347. Top K Frequent Elements

考察了优先队列stl的使用。
priority_queue

class Solution {public:    vector<int> topKFrequent(vector<int>& nums, int k) {        priority_queue <pair<int,int>> countQueue;        map<int,int> countMap;        vector<int> result;        for(int i=0;i<nums.size();i++)            countMap[nums[i]]++;        for(map<int,int>::iterator it=countMap.begin();it!=countMap.end();it++)        {            pair<int,int> temp(it->second,it->first);            countQueue.push(temp);            if(countQueue.size()>countMap.size()-k)            {                result.push_back(countQueue.top().second);                countQueue.pop();            }        }        return result;    }};