top-k-frequrent-elements solved

Author: kut7728

top-k-frequent-elements/kut7728.swift

@@ -0,0 +1,51 @@
+class Solution {
+    /*
+    1차 시도
+    복잡도 - O(n log n)
+    func topKFrequent(_ nums: [Int], _ k: Int) -> [Int] {
+        var list: [Int:Int] = [:]
+        var result: [Int] = []
+        if nums.count == 1 { return nums }
+
+        for i in nums {
+            list[i, default: 0] += 1
+        }
+
+        var sortedList = list.sorted { $0.value > $1.value }
+        print(sortedList)
+
+        for i in 0..<k {
+            let target = sortedList[i].key
+            result.append(target)
+            // sortedList[target] = 0
+        }
+        return result
+    } */
+    
+    // 2차 시도 : 복잡도 - O(n)
+    class Solution {
+        func topKFrequent(_ nums: [Int], _ k: Int) -> [Int] {
+            var freqMap = [Int: Int]()
+
+            for num in nums {
+                freqMap[num, default: 0] += 1
+            }
+            
+            // 버켓에 빈도수를 인덱스로 값을 저장
+            var buckets = Array(repeating: [Int](), count: nums.count + 1)
+            for (num, freq) in freqMap {
+                buckets[freq].append(num)
+            }
+            
+            var result = [Int]()
+            for i in (0 ..< buckets.count).reversed() {
+                result += buckets[i]
+                if result.count == k {
+                    break
+                }
+            }
+        
+            return result
+        }
+    }
+}