Sort) Quick Sort, Merge Sort, Heap Sort

1. 퀵 정렬 (Quick Sort): O(n log n) ~ O(n²)

def quick_sort(arr):
    if len(arr) <= 1:
        return arr
    pivot = arr[len(arr) // 2]
    left = [x for x in arr if x < pivot]
    middle = [x for x in arr if x == pivot]
    right = [x for x in arr if x > pivot]
    return quick_sort(left) + middle + quick_sort(right)

 

2. 병합 정렬 (Merge Sort): O(n log n)

def merge_sort(arr):
    if len(arr) <= 1:
        return arr

    mid = len(arr) // 2
    left = merge_sort(arr[:mid])
    right = merge_sort(arr[mid:])

    return merge(left, right)

def merge(left, right):
    sorted_arr = []
    i = j = 0

    while i < len(left) and j < len(right):
        if left[i] < right[j]:
            sorted_arr.append(left[i])
            i += 1
        else:
            sorted_arr.append(right[j])
            j += 1

    sorted_arr.extend(left[i:])
    sorted_arr.extend(right[j:])
    return sorted_arr

 

3. 힙 정렬 (Heap Sort): O(n log n)

import heapq

def heap_sort(arr):
    heapq.heapify(arr)  # 리스트를 힙으로 변환
    return [heapq.heappop(arr) for _ in range(len(arr))]