题目链接:http://acm.nyist.net/JudgeOnline/problem.php?pid=528
解题思路:
给你2个数,怎么判断它是否出现偶数次?
对1个数异或另一个数2次等于本身。
代码如下:
#include<iostream> #include<cstring> #include<cstdio> #include<map> #include<cmath> #include<algorithm> using namespace std; int Scan() { int res = 0 , ch; while( !( ( ch = getchar() ) >= '0' && ch <= '9' ) ) { if( ch == EOF ) return 1 << 30 ; } res = ch - '0' ; while( ( ch = getchar() ) >= '0' && ch <= '9' ) res = res * 10 + ( ch - '0' ) ; return res ; } int main() { int n, temp, x; while(scanf("%d", &n) != EOF) { temp = 0; for(int i = 0; i < n; ++i) { x = Scan(); temp ^= x; } printf("%d\n", temp); } return 0; }