寻找奇数
时间最优
#include<stdio.h>
inline int read(){
int x=0;char c=getchar();
while (c<'0'||c>'9') c=getchar();
while (c>='0'&&c<='9') x=x*10+c-'0',c=getchar();
return x;
}
int main() {
int res , n ;
n = read();
for (int i = 1 ; i <= n ; i ++) {
res ^= read();
}
printf("%d\n",res);
}