top-k-frequent-elements

Author: logerrors

src/top-k-frequent-elements/bench.cpp

@@ -5,7 +5,8 @@
 static void BM_solution(benchmark::State& state){
     auto s = std::make_shared<Solution>();
     for (auto _ : state) {
-
+        std::vector q = {1,1,1,2,2,3};
+        s->topKFrequent(q, 2);
     }
 }
 

src/top-k-frequent-elements/solution.hpp

@@ -2,9 +2,36 @@
 
 using namespace leetcode;
 
+
+class Compare{
+    public:
+        bool operator()(const std::pair<int,int>& lhs, const std::pair<int,int>& rhs){
+            return lhs.second > rhs.second;
+        }
+};
+
 class Solution {
 public:
     std::vector<int> topKFrequent(std::vector<int>& nums, int k) {
-        return {};
+        std::unordered_map<int,int> map;
+        for(auto num:nums){
+            map[num]++;
+        }
+
+        std::priority_queue<std::pair<int,int>, std::vector<std::pair<int,int>>, Compare> pq;
+        for(auto item:map){
+             pq.push(item);
+            if(pq.size() > k){
+                pq.pop();
+            }
+        }
+
+        std::vector<int> res(k);
+        for(int i = k - 1; i >= 0 ; i--){
+            res[i] = pq.top().first;
+            pq.pop();
+        }
+
+        return res;
     }
 };

src/top-k-frequent-elements/test.cpp

@@ -5,5 +5,7 @@
 
 TEST_CASE(__FILE__){
     auto s = std::make_shared<Solution>();
-    
+    std::vector a = {1,2};
+    std::vector q = {1,1,1,2,2,3};
+    REQUIRE(s->topKFrequent(q, 2) == a);
 }