hdu2509 Be the Winner

Total Submission(s): 1543    Accepted Submission(s): 817

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).
 
 
 
 
 
首先給出結論：先手勝若且唯若 ①所有堆石子數都為1且遊戲的SG值為0（即有偶數個孤單堆-每堆只有1個石子數）；②存在某堆石子數大於1且遊戲的SG值不為0.

證明：

因為先手勝。

#include <iostream>#include <stdio.h>#include <string.h>using namespace std;#define M 50int pri[M];int main(){   int tcase,i,ans,re,n;   while(scanf("%d",&n)!=EOF){        ans=0,re=0;        for(i=0;i<n;i++){            scanf("%d",&pri[i]);            if(pri[i]>1)            ans++;            re^=pri[i];        }        if(ans){            if(re)            printf("Yes\n");            else            printf("No\n");        }        else {            if(re)            printf("No\n");            else            printf("Yes\n");        }   }    return 0;}