Be the Winner(HDU-2509)

题面

Let’s consider m apples divided into n groups. Each group contains no more than 100 apples, arranged in a line. You can take any number of consecutive apples at one time. For example “@@@” can be turned into “@@” or “@” or “@ @"(two piles). two people get apples one after another and the one who takes the last is the loser. Fra wants to know in which situations he can win by playing strategies (that is, no matter what action the rival takes, fra will win).

输入

You will be given several cases. Each test case begins with a single number n (1 <= n <= 100), followed by a line with n numbers, the number of apples in each pile. There is a blank line between cases.

输出

If a winning strategies can be found, print a single line with “Yes”, otherwise print “No”.

样例输入

12
22 2
31
43

样例输出

1No
2Yes

提示

无

思路

Anti-Nim博弈，可以参见【题解】POJ-3480 John。

代码

 1using namespace std;
 2
 3int main()
 4{
 5    int n;
 6    for(~scanf("%d", &n))
 7    {
 8        int nim=0, anti=0;
 9        for(int i=0; i<n; i++){
10            int x; scanf("%d", &x);
11            if(x>1) anti = 1;
12            nim ^=x;
13        }
14        if((!nim&&!anti) || (nim&&anti)){
15            printf("Yes\n");
16        }else{
17            printf("No\n");
18        }
19    }
20    return 0;
21}