Top K Frequent Elements
Given a non-empty array of integers, return the k most frequent elements.
Example 1:
Input: nums = [1,1,1,2,2,3], k = 2 Output: [1,2]
Example 2:
Input: nums = [1], k = 1 Output: [1]
Note:
- You may assume k is always valid, 1 ≤ k ≤ number of unique elements.
- Your algorithm's time complexity must be better than O(n log n), where n is the array's size.
- It's guaranteed that the answer is unique, in other words,` the set of the top k frequent elements is unique.
- You can return the answer in any order.
class Solution {
public:
vector<int> topKFrequent(vector<int>& nums, int k) {
unordered_map<int,int> mp;
for(auto i:nums)
{
mp[i]++;
}
vector<int> ans;
vector<pair<int,int> > res;
for(auto p:mp)
{
res.push_back({p.first,p.second});
}
sort(res.begin(),res.end(),[](const pair<int ,int > &a ,const pair<int,int> &b)->bool{
return a.second>b.second;
});
for(int i=0;i<k;++i)
ans.push_back(res[i].first);
return ans;
}
};
