Top K Frequent Elements | Leetcode 347 | Priority Queue | Day-9

Time Complexity : O(nlogk)
Space Complexity : O(k)


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[none]

Best approach and explanation ever, thanks a lot

[code-a-mania]

Ohh crystal clear concept dude thank u for this😉🙂

[varadashtekar]

Thanks for providing optimized solution and explaining concept properly, Thank you

[Enigma-fkmh]

The reason why we are using the min heap because we want to pop the less frequent number not because its nlogn. Also if the question is asking for top less frequent number then we would use max heap because when we pop max heap the max frequent number will be popped

[ROHITGUPTA-zvdf]

vector<int> topKFrequent(vector<int>& nums, int k) {
unordered_map<int, int> mp;
vector<int> ans;
priority_queue<pair<int, int>> heap;
for(auto it:nums){
mp[it]++;
}
for(auto it: mp){
heap.push({it.second, it.first});
}

while(k>0){
int temp=heap.top().second;
heap.pop();
k--;
ans.push_back(temp);
}


return ans;
}

[madhurgupta]

Your code is better than LeetCode solution, I was not satisfied with their solution as they were using comparator and that was difficult to understand

[FirstnameLastname-rnqq]

I write my solution submit it
And watch your video to just look at it whether my intuition was like your or what could i have done better.

[hardiknegi]

why auto i is used in the first loop but auto & i in the second loop?

[shalabhbhatiya]

hy ayushi it may be wrong for maxheap we are popoing k time in maxheap so it will be klogn please correct of i am wrong

[edgyboi]

in max/min heap of pairs, do the nodes get sorted according to the first value of the pair always?

[pratyushpandey]

should we use min heap or max heap ? and why ?

[sagarbora]

hi ayushi
I think there we can optimize it in linear tc

[mohitsingh]

T.C : min-heap contains k-elements, we check for rest of all (N-K) elements.
when k is too larger i.e : K=N-1:
T.C:
T.C becomes O(N).
let me know I was wrong.