P2921-[USACO08DEC]在农场万圣节Trick or Treat on the Farm 

 1 #include <bits/stdc++.h>
 2 #define _for(i,a,b) for(int i = (a);i < b;i ++)
 3 #define _rep(i,a,b) for(int i = (a);i > b;i --)
 4 #define INF 0x3f3f3f3f
 5 #define pb push_back
 6 typedef long long ll;
 7 using namespace std;
 8 inline ll read()
 9 {
10     ll ans = 0;
11     char ch = getchar(), last = ' ';
12     while(!isdigit(ch)) last = ch, ch = getchar();
13     while(isdigit(ch)) ans = (ans << 1) + (ans << 3) + ch - '0', ch = getchar();
14     if(last == '-') ans = -ans;
15     return ans;
16 }
17 inline void write(ll x)
18 {
19     if(x < 0) x = -x, putchar('-');
20     if(x >= 10) write(x / 10);
21     putchar(x % 10 + '0');
22 }
23 
24 int N;
25 int ms[100003];
26 int G[100003];
27 int vis[100003];
28 int tmp[100003];
29 int passpoint;
30 int flag = 0;
31 int dfs(int nw,int len)
32 {
33     if(ms[nw])
34     {
35         flag = 1;
36         return ms[nw]+1;
37     }
38     if(vis[nw]==-1)
39     {
40         passpoint = nw;
41         ms[nw] = len-tmp[nw];
42         return len-tmp[nw];
43     }
44     tmp[nw] = len;
45     vis[nw] = -1;
46     ms[nw] = dfs(G[nw],len+1);
47     if(flag)
48         return ms[nw]+1;
49     tmp[nw] = 0;
50     if(passpoint==nw)
51     {
52         flag = 1;
53         return ms[nw]+1;
54     } 
55     return ms[nw];
56 }
57 int main()
58 {
59     N = read();
60     _for(i,1,N+1)
61         G[i] = read();
62     _for(i,1,N+1)
63         if(!ms[i])
64         {
65             flag = 0;
66             passpoint = -1;
67             dfs(i,0);
68         }
69 
70     _for(i,1,N+1)
71     printf("%d\n",ms[i]);
72 
73     return 0;
74 }

 

posted @ 2019-09-11 18:13  Asurudo  阅读(125)  评论(0)    收藏  举报