합병 정렬(Merge Sort) [임시]

정렬

def merge_sort(arr):
    if len(arr) <= 1:
        return arr
    mid = len(arr) // 2
    L = merge_sort(arr[:mid])
    R = merge_sort(arr[mid:])
    return merge(L, R)

def merge(a, b):
    res = []
    i = j = 0
    while i < len(a) and j < len(b):
        if a[i] <= b[j]:
            res.append(a[i]); i += 1
        else:
            res.append(b[j]); j += 1
    res += a[i:] + b[j:]
    return res