PAT甲级：1038 Recover the Smallest Number

题目描述：

Given a collection of number segments, you are supposed to recover the smallest number from them. For example, given { 32, 321, 3214, 0229, 87 }, we can recover many numbers such like 32-321-3214-0229-87 or 0229-32-87-321-3214 with respect to different orders of combinations of these segments, and the smallest number is 0229-321-3214-32-87.

Input Specification:

Each input file contains one test case. Each case gives a positive integer N (≤104) followed by N number segments. Each segment contains a non-negative integer of no more than 8 digits. All the numbers in a line are separated by a space.

Output Specification:

For each test case, print the smallest number in one line. Notice that the first digit must not be zero.

Sample Input:

5 32 321 3214 0229 87

Sample Output:

22932132143287

代码长度限制

16 KB

时间限制

200 ms

内存限制

64 MB

题目大意： 

题⽬⼤意：给⼀些字符串，求它们拼接起来构成最⼩数字的⽅式

解题思路： 

贪心

用 a + b < b + a 来判断a和b两个字符串的前后位置

Python3代码： 

import functools
lst = list(input().split())
N = int(lst[0]) ; lst = lst[1:]

def cmp(a,b) : # 自定义排序函数
    if a + b < b + a : return -1
    elif a + b == b + a : return 0
    else : return 1

lst.sort(key=functools.cmp_to_key(cmp))
ans = "".join(lst)
print(int(ans))