HDU 5795 A Simple Nim

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题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=5795

题意：一个n堆的取石子游戏，每次可以取一堆中的任意个，或者将当前堆分为三个非空堆。求先手/后手必胜。

思路：打表sg函数找规律。hihocoder上面有类似的题目，不过那个是分为两堆。

http://hihocoder.com/problemset/problem/1173

#include <cstdio>#include <cmath>#include <cstring>#include <string>#include <cstdlib>#include <iostream>#include <algorithm>#include <stack>#include <map>#include <set>#include <vector>#include <sstream>#include <queue>#include <utility>using namespace std;#define rep(i,j,k) for (int i=j;i<=k;i++)#define Rrep(i,j,k) for (int i=j;i>=k;i--)#define Clean(x,y) memset(x,y,sizeof(x))#define LL long long#define ULL unsigned long long#define inf 0x7fffffff#define mod 100000007//int sg[1009];////void init()//{//    sg[0] = 0;//    bool f[1009];//    rep(i,1,100)//    {//        Clean(f,false);//        rep(j,1,i)//            f[ sg[i-j] ] = true;//        if ( i >= 3 )//        {//            rep(j,1,i-2)//                rep(k,1,i-2)//                if ( j+k < i )//                    f[ sg[j] ^ sg[k] ^ sg[i-j-k] ] = true;//        }//        int j = 0;//        while ( f[j] ) j++;//        sg[i] = j;//        cout<<i<<" : "<<sg[i]<<endl;//    }//}int main(){    //init();    int T,n,temp;    cin>>T;    while(T--)    {        int ans = 0;        scanf("%d",&n);        rep(i,1,n)        {            scanf("%d",&temp);            if ( temp % 8 == 0 )                ans ^= temp-1;            else if ( temp % 8 == 7 )                ans ^= temp + 1;            else ans ^= temp;        }        puts( ans ? "First player wins." : "Second player wins." );    }    return 0;}

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