HDU 2176

http://acm.hdu.edu.cn/showproblem.php?pid=2176

nim博弈的模型。要输出先手第一次取的情况，考虑角度是留给对手必败态

#include <iostream>

#include <cstdio>



using namespace std;



int a[200005];



int main() {

    int m;

    while(~scanf("%d", &m), m) {

        int s = 0;

        for(int i = 0; i < m; i++) {

            scanf("%d", &a[i]);

            s ^= a[i];

        }        

        if(!s) puts("No");

        else {

            puts("Yes");

            for(int i = 0; i < m; i++) {

                int st = s ^ a[i];

                if(st < a[i]) printf("%d %d\n", a[i], st);

            }

        }

    }

    return 0;

}

View Code