feat: top-k-frequent-elements

Author: changchanghwang

top-k-frequent-elements/changchanghwang.go

@@ -0,0 +1,25 @@
+// Time: O(nlogn)
+// Space: O(n)
+func topKFrequent(nums []int, k int) []int {
+	hashMap := map[int]int{}
+	for _, num := range nums {
+		hashMap[num]++
+	}
+
+	result := [][]int{}
+
+	for key, value := range hashMap {
+		result = append(result, []int{key, value})
+	}
+
+	sort.Slice(result, func(i, j int) bool { // go의 sort는 quicksort를 기본적으로 사용한다. O(nlogn)
+		return result[i][1] > result[j][1]
+	})
+
+	resultNums := []int{}
+	for i := 0; i < k; i++ {
+		resultNums = append(resultNums, result[i][0])
+	}
+
+	return resultNums[:k]
+}