Python实现Pat 1041. Be Unique (20)

喜欢ヅ旅行 2022-06-04 08:40 123阅读 0赞

### [题目][Link 1] ###

Being unique is so important to people on Mars that even their lottery is designed in a unique way. The rule of winning is simple: one bets on a number chosen from \[1, 104\]. The first one who bets on a unique number wins. For example, if there are 7 people betting on 5 31 5 88 67 88 17, then the second one who bets on 31 wins.

Input Specification:

Each input file contains one test case. Each case contains a line which begins with a positive integer N (<=105) and then followed by N bets. The numbers are separated by a space.

Output Specification:

For each test case, print the winning number in a line. If there is no winner, print “None” instead.

Sample Input 1:  
7 5 31 5 88 67 88 17  
Sample Output 1:  
31  
Sample Input 2:  
5 888 666 666 888 888  
Sample Output 2:  
None

### 解答1，会超时 ###

#直接检查每一个数值点是否唯一
    line=[int(x) for x in input().split(' ')]
    N=line[0]
    seq=line[1:]
    for i in range(N):
        tmp=seq[:]
        tmp.pop(i)
        if seq[i] not in tmp:
            print (seq[i])
            break
    else:
        print(None)

![这里写图片描述][SouthEast]

### 解答2 ###

#利用哈希映射，统计各数值点出现的次数，再检查次数是否为1
    line=[int(x) for x in input().split(' ')]
    N=line[0]
    seq=line[1:]
    tag=[0]*100000#一个恰当大的数值，过小返回非零，过大内存超限
    for c in seq:
        tag[c]+=1
    for i in range(N):
        if tag[seq[i]]==1:
            print(seq[i])
            break
    else:
        print(None)

![这里写图片描述][SouthEast 1]

[Link 1]: https://www.patest.cn/contests/pat-a-practise/1034
[SouthEast]: /images/20220604/2712fccf6c924b52b40fded0f93ca9a1.png
[SouthEast 1]: /images/20220604/6ca2ce2c672845c4a93826e3a07e7d30.png