Python练习题——数组拼接

#
# 输入一个正整数数组，把数组里所有数字拼接起来排成一个数，打印能拼接出的所有数字中最小的一个。
#
# 示例 1:
# 输入: [10,2]
# 输出: "102"
#
# 示例2:
# 输入: [3,30,34,5,9]
# 输出: "3033459"

# #1
# class Solution:
#     def minNumber(self, nums):
#         nums_str=[str(i) for i in nums]#数组数字转字符串
#         for i in range(len(nums)-1):
#             for j in range(i+1,len(nums)):
#                 if nums_str[i]+nums_str[j]>nums_str[j]+nums_str[i]:#字符串拼接比较大小
#                     nums_str[i],nums_str[j]=nums_str[j],nums_str[i]#根据拼接比较结果，小数在前大数在后
#         output=''.join(nums_str)#拼接字符串
#         return output
# # nums=[3,30,34,5,9]
# nums=[58,7,3,30,34]
# s=Solution()
# output=s.minNumber(nums)
# print(output)
#
#
# #2
# class cmpSmaller(str):
#     def __lt__(self, y):#富比较方法
#         # print('self=',self)
#         # print('y=',y)
#         return self + y < y + self  # 字符串拼接比较(两两比较)
#     # 按由小到大来排列
# class Solution:
#     def minNumber(self, nums):
#         res=sorted(map(str, nums),key=cmpSmaller)
#         smallest = ''.join(res)
#         return smallest
# nums=[58,7,3,30,34]
# s=Solution()
# output=s.minNumber(nums)
# print(output)
#
#
# #3
# import itertools
# def fun1(a):
#     # itertools.permutations(iterable, r)
#     # 第一个参数为可迭代对象，第二个参数为参与排列的元素的个数，r的默认值为可迭代对象的长度，即全排列
#     # 返回一个元素类型为元组的迭代器
#     b = []
#     full_permutation = list(itertools.permutations(a,len(a)))
#     # print(full_permutation)
#     for i in full_permutation:
#         b.append(''.join([str(n) for n in i]))
#     return sorted(b)[0]
# a = [3,31,34,5,9]
# res = fun1(a)
# print(res)
#
#
# #4
# import functools
# def minNumber(nums):
#     def sort_rule(x, y):
#         a, b = x + y, y + x
#         if a > b:
#             return 1
#         elif a < b:
#             return -1
#         else:
#             return 0
#     strs = [str(num) for num in nums]
#     strs.sort(key=functools.cmp_to_key(sort_rule),reverse=False)
#     return ''.join(strs)
# print(minNumber([3,31,34,5,112]))