hdu 1524 A Chess Game 博弈

题目链接

给出一个有向无环图， 上面放有一些棋子， 两个人轮流移动棋子， 当一个人无法移动时， 算输。

求出每一个点的sg值， 异或就可以。出度为0的点sg值为0。

#include<bits/stdc++.h>
using namespace std;
#define pb(x) push_back(x)
#define ll long long
#define mk(x, y) make_pair(x, y)
#define lson l, m, rt<<1
#define mem(a) memset(a, 0, sizeof(a))
#define rson m+1, r, rt<<1|1
#define mem1(a) memset(a, -1, sizeof(a))
#define mem2(a) memset(a, 0x3f, sizeof(a))
#define rep(i, a, n) for(int i = a; i<n; i++)
#define ull unsigned long long
typedef pair<int, int> pll;
const double PI = acos(-1.0);
const double eps = 1e-8;
const int mod = 1e9+7;
const int inf = 1061109567;
const int dir[][2] = { {-1, 0}, {1, 0}, {0, -1}, {0, 1} };
const int maxn = 1e6+5;
int head[maxn], sg[1005], num;
struct node
{
    int to, nextt;
}e[maxn];
void init() {
    mem1(head);
    num = 0;
    mem1(sg);
}
void add(int u, int v) {
    e[num].to = v;
    e[num].nextt = head[u];
    head[u] = num++;
}
int mex(int x) {
    if(~sg[x])
        return sg[x];
    bool vis[1005];
    memset(vis, false, sizeof(vis));
    for(int i = head[x]; ~i; i = e[i].nextt) {
        int v = e[i].to;
        if(sg[v]==-1)
            sg[v] = mex(v);
        vis[sg[v]] = 1;
    }
    for(int i = 0; ; i++)
        if(!vis[i])
            return i;
}
int main()
{
    int n, x, y;
    while(scanf("%d", &n)!=EOF) {
        init();
        for(int i = 0; i<n; i++) {
            scanf("%d", &x);
            while(x--) {
                scanf("%d", &y);
                add(i, y);
            }
        }
        while(scanf("%d", &x)&&x) {
            int ans = 0;
            for(int i = 0; i<x; i++) {
                scanf("%d", &y);
                ans ^= mex(y);
            }
            if(ans) {
                puts("WIN");
            } else {
                puts("LOSE");
            }
        }
    }
}