HDU 3032 (Nim博弈变形) Nim or not Nim?

 1 #include <cstdio>
 2 #include <cstring>
 3 
 4 const int maxn = 100;
 5 int sg[maxn * 2];
 6 bool vis[maxn * 2];
 7 
 8 int mex(int v)
 9 {
10     if(sg[v] != -1) return sg[v];
11     memset(vis, false, sizeof(vis));
12     for(int i = 0; i < v; i++) vis[mex(i)] = true;
13     for(int i = 1; v - i >= i; i++) vis[mex(i) ^ mex(v - i)] = true;
14     for(int i = 0; ; i++) if(!vis[i]) { sg[v] = i; return i; }
15 }
16 
17 int main()
18 {
19     memset(sg, -1, sizeof(sg));
20     sg[0] = 0;
21     for(int i = 0; i < maxn; i++)
22         printf("%d %d\n", i, mex(i));
23 
24     return 0;
25 }

 1 #include <cstdio>
 2 
 3 inline long long SG(long long x)
 4 {
 5     if(x == 0) return 0;
 6     if(x % 4 == 3) return x + 1;
 7     if(x % 4 == 0) return x - 1;
 8     return x;
 9 }
10 
11 int main()
12 {
13     //freopen("in.txt", "r", stdin);
14 
15     int T; scanf("%d", &T);
16     while(T--)
17     {
18         int n; scanf("%d", &n);
19         long long ans = 0, x;
20         for(int i = 0; i < n; i++)
21         {
22             scanf("%lld", &x);
23             ans ^= SG(x);
24         }
25         printf("%s\n", ans ? "Alice" : "Bob");
26     }
27 
28     return 0;
29 }