Codeforces-936B Sleepy Game

Posted 2020-10-27 xFANx

传送门

 

n点m边的有向图，

如果  一个玩家能从起点出发，走奇数步后不能再行动，

　　输出Win

　　输出路径

否则如果  一个玩家能走无限步 

　　输出Draw

否则 

　　输出Lose

 

跑一遍dfs并判环

 1 #include <cstdio>
 2 #include <vector>
 3 #include <cstring>
 4 #include <algorithm>
 5 using namespace std;
 6 typedef long long LL;
 7 
 8 const int maxn = 1e5 + 10;
 9 vector<int> G[maxn];
10 
11 int n, m;
12 bool draw;
13 bool out[maxn];
14 bool dp[maxn][2];
15 int vis[maxn][2], nxt[maxn][2];
16 
17 bool dfs(int x, int s) {
18     if (!out[x]) return s == 1;
19     if (vis[x][s] == 2) return dp[x][s];
20     vis[x][s] = 1;
21     bool flag = 0;
22     for (int i = 0; i < G[x].size(); i++) {
23         int to = G[x][i];
24         if (vis[to][s ^ 1] == 1) {//注意不能为2
25             draw = 1;
26             continue; 
27         }
28         if (dfs(to, s ^ 1)) {
29             flag = 1;
30             nxt[x][s] = to;
31         }
32     }
33     vis[x][s] = 2;
34     return dp[x][s] = flag;
35 }
36 
37 void print(int x, int s) {
38     printf("%d", x);
39     if (nxt[x][s]) {
40         printf(" ");
41         print(nxt[x][s], s ^ 1);
42     } else {
43         puts("");
44     }
45 }
46 
47 
48 
49 int main() {
50     scanf("%d%d", &n, &m);
51     for (int i = 1; i <= n; i++) {
52         int cnt;
53         scanf("%d", &cnt);
54         if (cnt) out[i] = 1;
55         while (cnt--) {
56             int to;
57             scanf("%d", &to);
58             G[i].push_back(to);
59         }
60     }
61     int st;
62     scanf("%d", &st);
63     if (dfs(st, 0)) {
64         puts("Win");
65         print(st, 0);
66     } else if (draw) {
67         puts("Draw");
68     } else {
69         puts("Lose");
70     }
71 
72     return 0;
73 }