Luogu 2575 高手过招-SG函数

Solution

SG函数跑一遍就过了ouo

Code

#include<cstring>
#include<cstdio>
#include<algorithm>
#define rd read()
#define cl(a) memset(a, 0, sizeof(a));
using namespace std;

const int N = 1 << 21;

int SG[N], S[500];
int T, n;

int read() {
    int X = 0, p = 1; char c = getchar();
    for(; c > '9' ||  c < '0'; c = getchar()) if(c == '-') p = -1;
    for(; c >= '0' && c <= '9'; c = getchar()) X = X * 10 + c - '0';
    return X * p;
}

void mkSG() {
    for(int i = 0; i < 20; ++i) SG[i] = 0;
    for(int i = 1; i < (1 << 20); ++i) {
        cl(S);
        int last = -1, nt;
        for(int j = 0; j < 20; ++j) if((i >> j) & 1) {
            if(~last) {
                nt = i | (1 << last);
                nt ^= 1 << j;
                S[SG[nt]] = 1;
            }
        } else last = j;
        int j = 0;
        for(; S[j]; ++j);
        SG[i] = j;
    }
}

int main()
{
    mkSG();
    T = rd;
    for(; T; T--) {
        n = rd;
        int ans = 0;
        for(int i = 1; i <= n; ++i) {
            int m = rd, tmp = 0;
            for(int j = 1; j <= m; ++j) {
                int x = rd;
                tmp |= 1 << (20 - x);    
            }
            ans ^= SG[tmp];
        }
        if(ans) puts("YES");
        else puts("NO");
    }
}