在Python中查找mergesort中的中间点

def merge_sort(arr):
    if len(arr) <= 1:
        return arr
    
    mid = find_midpoint(arr)
    left = arr[:mid]
    right = arr[mid:]
    
    left = merge_sort(left)
    right = merge_sort(right)
    
    return merge(left, right)

def find_midpoint(arr):
    slow = fast = 0
    while fast < len(arr) and fast + 1 < len(arr):
        slow += 1
        fast += 2
    return slow

def merge(left, right):
    merged = []
    i = j = 0
    while i < len(left) and j < len(right):
        if left[i] < right[j]:
            merged.append(left[i])
            i += 1
        else:
            merged.append(right[j])
            j += 1
    merged.extend(left[i:])
    merged.extend(right[j:])
    return merged

# 示例用法
arr = [4, 2, 7, 1, 5, 3]
sorted_arr = merge_sort(arr)
print(sorted_arr)