Codeforces Round #242 (Div. 2) C Magic Formulas

 1 #include <iostream>

 2 #include <stdio.h>

 3 #include <string.h>

 4 using namespace std;

 5 int array[1000001];

 6 int main(){

 7     int cnt, i, j, k, t, n, num;

 8     int temp = 0;

 9     for(k = 0 ;k <= 1000000 ; k++){

10         temp ^= k;

11         array[k] = temp;

12     }

13     while(EOF != scanf("%d",&n)){

14         cnt = 0;

15         for(i = 1; i <= n; i++){

16             scanf("%d",&num);

17             cnt ^= num;

18         }

19         for(i = 1 ;i <= n; i++){

20             int tmp_q = n / i;

21             int tmp_w = n % i;

22             while(tmp_q--){

23                 cnt ^= array[i-1];

24             }

25             if(tmp_w)

26                 cnt ^= array[tmp_w];

27         }

28         printf("%d
",cnt);

29     }

30     return 0;

31 }