hdu 3980 Paint Chain sg函数

 1 #include<bits/stdc++.h>
 2 using namespace std;
 3 #define pb(x) push_back(x)
 4 #define ll long long
 5 #define mk(x, y) make_pair(x, y)
 6 #define lson l, m, rt<<1
 7 #define mem(a) memset(a, 0, sizeof(a))
 8 #define rson m+1, r, rt<<1|1
 9 #define mem1(a) memset(a, -1, sizeof(a))
10 #define mem2(a) memset(a, 0x3f, sizeof(a))
11 #define rep(i, a, n) for(int i = a; i<n; i++)
12 #define ull unsigned long long
13 typedef pair<int, int> pll;
14 const double PI = acos(-1.0);
15 const double eps = 1e-8;
16 const int mod = 1e9+7;
17 const int inf = 1061109567;
18 const int dir[][2] = { {-1, 0}, {1, 0}, {0, -1}, {0, 1} };
19 int sg[1005], m;
20 int mex(int x) {
21     if(~sg[x])
22         return sg[x];
23     if(x<m)
24         return sg[x] = 0;
25     int vis[1000];
26     mem(vis);
27     for(int i = 0; i<=x-m; i++) {
28         vis[mex(i)^mex(x-m-i)] = 1;         //相当于把一堆个数为x的石子分成两堆， 一堆个数为i， 另一堆为x-m-i
29     }
30     int i = 0;
31     while(1) {
32         if(!vis[i])
33             return sg[x] = i;
34         i++;
35     }
36 }
37 int main()
38 {
39     int t, n, cnt = 1;
40     cin>>t;
41     while(t--) {
42         mem1(sg);
43         scanf("%d%d", &n, &m);
44         printf("Case #%d: ", cnt++);
45         if(n<m) {
46             puts("abcdxyzk");
47             continue;
48         }
49         sg[n-m] = mex(n-m);
50         if(!sg[n-m]) {
51             puts("aekdycoin");
52         } else {
53             puts("abcdxyzk");
54         }
55     }
56     return 0;
57 }