cogs 2039. 树的统计

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<algorithm>
 4 #include<cmath>
 5 #include<cstring>
 6 #include<string>
 7 #include<queue>
 8 
 9 using namespace std;
10 const int N=100010;
11 
12 int head[N];
13 int now=1;
14 int n;
15 queue<int>q;
16 int tot;
17 
18 struct node 
19 {
20     int u,v,nxt;
21 } E[N];
22 
23 inline int read() 
24 {
25     int x=0,f=1;
26     char c=getchar();
27     while(c<‘0‘||c>‘9‘) 
28     {
29         if(c==‘-‘)f=-1;
30         c=getchar();
31     }
32     while(c>=‘0‘&&c<=‘9‘)x=x*10+c-‘0‘,c=getchar();
33     return x*f;
34 }
35 
36 inline void add(int u,int v) 
37 {
38     E[now].u=u;
39     E[now].v=v;
40     E[now].nxt=head[u];
41     head[u]=now;
42     now++;
43 }
44 
45 inline void bfs(int x) 
46 {
47     tot=0;
48     q.push(x);
49     while(!q.empty()) 
50     {
51         int top=q.front();
52         q.pop();
53         if(top<x)tot++;
54         for(int i=head[top]; i!=-1; i=E[i].nxt) 
55         {
56             int v=E[i].v;
57             q.push(v);
58         }
59     }
60     printf("%d\n",tot);
61 
62 }
63 
64 int main() 
65 {
66     freopen("counttree.in","r",stdin);
67     freopen("counttree.out","w",stdout);
68 
69     n=read();
70 
71     for(int i=1; i<=n; i++)
72         head[i]=-1;
73     for(int i=1; i<=n; i++) 
74     {
75         int u=read();
76         add(u,i);
77     }
78 
79     for(int i=1; i<=n; i++) 
80         bfs(i);
81 
82     return 0;
83 
84 }

 1 #include<algorithm>
 2 #include<cstdio>
 3 #define maxn 100001
 4 
 5 using namespace std;
 6 
 7 struct Edge
 8 {
 9     int vi;
10     int vj;
11     int next;
12 }edge[maxn * 4];
13 
14 int topedge = 0;int topx = 0;
15 int dfsx[maxn * 5];int b[maxn];int e[maxn];//在dfs序中出现次序 0
16 int head[maxn];
17 int kai;int N;
18 
19 inline int read()
20 {
21     int x=0,f=1;
22     char c=getchar();
23     while(c<‘0‘||c>‘9‘){if(c==‘-‘)f=-1;c=getchar();}
24     while(c>=‘0‘&&c<=‘9‘)x=x*10+c-‘0‘,c=getchar();
25     return x*f;
26 }
27 
28 void push(int vi,int vj)
29 {
30     topedge ++;
31     edge[topedge].vj = vj;
32     edge[topedge].next = head[vi];
33     head[vi] = topedge;
34 }
35 
36 void dfs(int x)
37 {
38     dfsx[++topx] = x;
39     b[x] = topx;
40     for(int i = head[x];i != 0 ;i = edge[i].next)
41     {
42         dfs(edge[i].vj);
43     }
44     e[x] = topx;
45 }
46 
47 int main()
48 {
49     freopen("counttree.in","r",stdin);
50     freopen("counttree.out","w",stdout);
51     N = read();
52     for(int i = 1;i <= N;i ++)
53     {
54         int num = read();
55         if(num == 0)
56         {
57           kai = i;
58           continue;    
59         }
60         push(num,i);
61     }
62     dfs(kai);
63     for(int i = 1;i <= N;i ++)
64     {
65         int answ = 0;
66         for(int j = b[i] + 1;j <= e[i];j ++)
67             if(dfsx[j] < i)
68                 answ ++;
69         printf("%d\n",answ);
70     }
71     return 0;
72 }