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-;
 const int mod = 1e9+;
 const int inf = ;
 const int dir[][] = { {-, }, {, }, {, -}, {, } };
 const int maxn = 1e6+;
 int head[maxn], sg[], num;
 struct node
 {
     int to, nextt;
 }e[maxn];
 void init() {
     mem1(head);
     num = ;
     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[];
     memset(vis, false, sizeof(vis));
     for(int i = head[x]; ~i; i = e[i].nextt) {
         int v = e[i].to;
         if(sg[v]==-)
             sg[v] = mex(v);
         vis[sg[v]] = ;
     }
     for(int i = ; ; i++)
         if(!vis[i])
             return i;
 }
 int main()
 {
     int n, x, y;
     while(scanf("%d", &n)!=EOF) {
         init();
         for(int i = ; i<n; i++) {
             scanf("%d", &x);
             while(x--) {
                 scanf("%d", &y);
                 add(i, y);
             }
         }
         while(scanf("%d", &x)&&x) {
             int ans = ;
             for(int i = ; i<x; i++) {
                 scanf("%d", &y);
                 ans ^= mex(y);
             }
             if(ans) {
                 puts("WIN");
             } else {
                 puts("LOSE");
             }
         }
     }
 }