力扣刷题记录34.1-----347. 前 K 个高频元素

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一、题目

二、代码

class Solution 
{
public:
    vector<int> topKFrequent(vector<int>& nums, int k)
    {

        int i,j;
        int nums_size;

        vector<int> return_vector;
        map<int,int> map_for_count;
        map<int, int>::iterator pos;
        int temp_num;
        int max_frequency=0;

        nums_size=nums.size();
        for(i=0;i<nums_size;i++)   //建立字典map
        {
            // cout<<"  here "<
            temp_num=nums[i];
            pos=map_for_count.find(temp_num);
            if(pos!=map_for_count.end())    //如果找到了  
            {
              pos->second++; 
            // cout<<"  here "<
            }
            else    //如果没有找到 新建map
            {

              map_for_count.insert(pair<int,int>(temp_num,1));
            // cout<<"  here "<
            }
        }
       

       for(i=0;i<k;i++)
       {
            max_frequency=0;
            for(map<int,int>::iterator it=map_for_count.begin();it!=map_for_count.end();it++)
            {
            // cout<<"key=  "<first<<"value=  "<second<
                if(it->second>max_frequency)  //找到大的替换
                {
                    max_frequency=it->second;//更新最大值
                    pos=it; //更新地址  地址在外部就无法erase 很难说为什么
                  //  std::cout<<"pos->first  "<first<<"pos->second  "<second;
                    
                }
            }
           
           return_vector.push_back(pos->first);
           //std::cout<<"pos->first  "<first<<"pos->second  "<second;
           map_for_count.erase(pos);
       }

        return return_vector;
    }
};

三、运行结果