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 [1,10^4]. 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 (≤10^5) and then followed by Nbets. 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
题意:
给出N (≤10^5) 个数字from [1,10^4].,问按照读入的顺序,哪个数字是第一个在所有数字中只出现一次的数字。如果所有数字出现的次数均超过一次,则输出“None”.
注意:
- 数字最大取到10000,因此散列数组至少开到10001
- 采用散列数组在读入数字时,记录该数字的出现次数。但注意本题要求输出第一个,采用 a[100001] 按顺序记录输入的数字
#include <cstdio>
int a[100001], hasnTable[10001] = {0};
int main(){
int n;
scanf("%d", &n);
for(int i = 0; i < n; i++){
scanf("%d", &a[i]);
hasnTable[a[i]]++;
}
int ans = -1;
for(int i = 0; i < n; i++){
if(hasnTable[a[i]] == 1){
ans = a[i];
break;
}
}
if(ans == -1)
printf("None");
else
printf("%d\n", ans);
return 0;
}