如何查找表中没有逆序对的对？

def merge_sort(arr):
    if len(arr) <= 1:
        return arr, 0
    
    mid = len(arr) // 2
    left, count_left = merge_sort(arr[:mid])
    right, count_right = merge_sort(arr[mid:])
    
    merged, count_merge = merge(left, right)
    
    return merged, count_left + count_right + count_merge

def merge(left, right):
    merged = []
    count = 0
    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])
            count += len(left) - i
            j += 1
    
    merged.extend(left[i:])
    merged.extend(right[j:])
    
    return merged, count

# 示例输入
arr = [4, 2, 1, 3, 5]

# 调用归并排序函数
sorted_arr, count = merge_sort(arr)

if count == 0:
    print("表中没有逆序对的对")
else:
    print("表中存在逆序对的对")