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HDU 3032 Nim or not Nim?(sg函数)

题目链接

暴力出来,竟然眼花了以为sg(i) = i啊....看表要认真啊!!!

#include <cstdio>
#include <cstring>
#include <iostream>
using namespace std;
#define LL __int64
int dp[10001];
int sg(int x)
{
    int flag[10001],temp,i;
    if(dp[x] >= 0)
    return dp[x];
    memset(flag,0,sizeof(flag));
    for(i = 1;i <= x;i ++)
    {
        temp = sg(x-i);
        flag[temp] = 1;
    }
    for(i = 1;i < x;i ++)
    {
        temp = sg(i)^sg(x-i);
        flag[temp] = 1;
    }
    for(i = 0;;i ++)
    if(!flag[i])
    return dp[x] = i;
}
int main()
{
    int n,m,i,ans,t;
    scanf("%d",&t);
    while(t--)
    {
        scanf("%d",&n);
        ans = 0;
        for(i = 0;i < n;i ++)
        {
            scanf("%d",&m);
            if(m%4 == 0)
            m --;
            else if((m+1)%4 == 0)
            m ++;
            ans ^= m;
        }
        if(ans)
        printf("Alice\n");
        else
        printf("Bob\n");
    }
    return 0;
}
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