Luogu 2575 高手过招-SG函数

Posted 2021-01-04 cychester

Solution

SG函数跑一遍就过了ouo

 

Code

 1 #include<cstring>
 2 #include<cstdio>
 3 #include<algorithm>
 4 #define rd read()
 5 #define cl(a) memset(a, 0, sizeof(a));
 6 using namespace std;
 7 
 8 const int N = 1 << 21;
 9 
10 int SG[N], S[500];
11 int T, n;
12 
13 int read() {
14     int X = 0, p = 1; char c = getchar();
15     for(; c > ‘9‘ ||  c < ‘0‘; c = getchar()) if(c == ‘-‘) p = -1;
16     for(; c >= ‘0‘ && c <= ‘9‘; c = getchar()) X = X * 10 + c - ‘0‘;
17     return X * p;
18 }
19 
20 void mkSG() {
21     for(int i = 0; i < 20; ++i) SG[i] = 0;
22     for(int i = 1; i < (1 << 20); ++i) {
23         cl(S);
24         int last = -1, nt;
25         for(int j = 0; j < 20; ++j) if((i >> j) & 1) {
26             if(~last) {
27                 nt = i | (1 << last);
28                 nt ^= 1 << j;
29                 S[SG[nt]] = 1;
30             }
31         } else last = j;
32         int j = 0;
33         for(; S[j]; ++j);
34         SG[i] = j;
35     }
36 }
37 
38 int main()
39 {
40     mkSG();
41     T = rd;
42     for(; T; T--) {
43         n = rd;
44         int ans = 0;
45         for(int i = 1; i <= n; ++i) {
46             int m = rd, tmp = 0;
47             for(int j = 1; j <= m; ++j) {
48                 int x = rd;
49                 tmp |= 1 << (20 - x);    
50             }
51             ans ^= SG[tmp];
52         }
53         if(ans) puts("YES");
54         else puts("NO");
55     }
56 }

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