692. Top K Frequent Words
Problem Statement
Given an array of strings words
and an integer k
, return the k
most frequent strings.
Return the answer sorted by the frequency from highest to lowest. Sort the words with the same frequency by their lexicographical order.
Example 1:
Input: words = ["i","love","leetcode","i","love","coding"], k = 2
Output: ["i","love"]
Explanation: "i" and "love" are the two most frequent words.
Note that "i" comes before "love" due to a lower alphabetical order.
Example 2:
Input: words = ["the","day","is","sunny","the","the","the","sunny","is","is"], k = 4
Output: ["the","is","sunny","day"]
Explanation: "the", "is", "sunny" and "day" are the four most frequent words, with the number of occurrence being 4, 3, 2 and 1 respectively.
Constraints:
1 <= words.length <= 500
1 <= words[i].length <= 10
words[i]
consists of lowercase English letters.k
is in the range[1, The number of
unique
words[i]]
Follow-up: Could you solve it in O(n log(k))
time and O(n)
extra space?
Intuition
Approach:
Custom Comparator
Links
https://leetcode.com/problems/top-k-frequent-words/description/
Video Links
Approach 1:
typedef pair<int, string> pis;
struct Comp {
bool operator()(const pair<int, string>& p1, const pair<int, string>& p2) {
// Compare integers in descending order
if (p1.first != p2.first) {
return p1.first < p2.first; // Change to > for ascending order
}
// If integers are equal, compare strings in ascending order
return p1.second > p2.second; // Change to < for descending order
}
};
class Solution {
public:
vector<string> topKFrequent(vector<string>& arr, int k) {
vector<string> ans;
unordered_map<string, int> mp;
priority_queue<pis, vector<pis>, Comp> pq;
for(auto &it: arr)
mp[it]++;
for(auto &it: mp)
pq.push({it.second, it.first});
while(k--){
ans.push_back(pq.top().second);
pq.pop();
}
return ans;
}
};
Approach 2:
Approach 3:
Approach 4:
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