C. Kefa and Park
2015-11-30 18:26
399 查看
time limit per test
2 seconds
memory limit per test
256 megabytes
input
standard input
output
standard output
Kefa decided to celebrate his first big salary by going to the restaurant.
He lives by an unusual park. The park is a rooted tree consisting of n vertices with the root at vertex 1.
Vertex 1 also contains Kefa's house. Unfortunaely for our hero, the park also contains cats. Kefa has already found out what are the vertices
with cats in them.
The leaf vertices of the park contain restaurants. Kefa wants to choose a restaurant where he will go, but unfortunately he is very afraid of cats, so there is no way he will go to the restaurant if the path from the restaurant to his house contains more than m consecutive vertices
with cats.
Your task is to help Kefa count the number of restaurants where he can go.
Input
The first line contains two integers, n and m (2 ≤ n ≤ 105, 1 ≤ m ≤ n)
— the number of vertices of the tree and the maximum number of consecutive vertices with cats that is still ok for Kefa.
The second line contains n integers a1, a2, ..., an,
where each ai either
equals to 0 (then vertex i has
no cat), or equals to 1 (then vertex i has
a cat).
Next n - 1 lines contains the edges of the tree in the format "xi yi"
(without the quotes) (1 ≤ xi, yi ≤ n, xi ≠ yi),
where xiand yi are
the vertices of the tree, connected by an edge.
It is guaranteed that the given set of edges specifies a tree.
Output
A single integer — the number of distinct leaves of a tree the path to which from Kefa's home contains at most mconsecutive vertices
with cats.
Sample test(s)
input
output
input
output
Note
Let us remind you that a tree is a connected graph on n vertices and n - 1 edge.
A rooted tree is a tree with a special vertex called root. In a rooted tree among any two vertices connected by an edge, one vertex
is a parent (the one closer to the root), and the other one is a child. A vertex is called a leaf, if it has no children.
Note to the first sample test:
The vertices containing cats are marked red. The restaurants
are at vertices 2, 3, 4. Kefa can't go only to the restaurant located at vertex 2.
Note to the second sample test:
The restaurants are located at vertices 4, 5, 6, 7. Kefa
can't go to restaurants 6, 7.
解题说明:此题是图论题,建一棵树,然后对树进行深度优先搜索题,由于一条路上不能连续出现k只猫,遍历路径时进行判断。如果走到了叶子那就得到了满足条件的一条路径。
#include<cstdio>
#include <cstring>
#include<iostream>
#include<algorithm>
#include<vector>
using namespace std;
int n,m,x,y,cnt,a[100005];
vector<int> b[100005];
void dfs(int p,int q,int pr)
{
int i,k,sz = b[p].size();
if(q > m)
{
return;
}
if(sz == 1 && p != 1)
{
cnt++;
return;
}
for(i=0; i<sz; i++)
{
k = b[p][i];
if(k == pr)
{
continue;
}
if(a[k])
{
dfs(k,q+1,p);
}
else
{
dfs(k,0,p);
}
}
}
int main()
{
int i;
cin>>n>>m;
for(i=1; i<=n; i++)
{
scanf("%d",&a[i]);
}
for(i=1; i<n; i++)
{
scanf("%d%d",&x,&y);
b[x].push_back(y);
b[y].push_back(x);
}
dfs(1,a[1],0);
cout<<cnt<<endl;
return 0;
}
2 seconds
memory limit per test
256 megabytes
input
standard input
output
standard output
Kefa decided to celebrate his first big salary by going to the restaurant.
He lives by an unusual park. The park is a rooted tree consisting of n vertices with the root at vertex 1.
Vertex 1 also contains Kefa's house. Unfortunaely for our hero, the park also contains cats. Kefa has already found out what are the vertices
with cats in them.
The leaf vertices of the park contain restaurants. Kefa wants to choose a restaurant where he will go, but unfortunately he is very afraid of cats, so there is no way he will go to the restaurant if the path from the restaurant to his house contains more than m consecutive vertices
with cats.
Your task is to help Kefa count the number of restaurants where he can go.
Input
The first line contains two integers, n and m (2 ≤ n ≤ 105, 1 ≤ m ≤ n)
— the number of vertices of the tree and the maximum number of consecutive vertices with cats that is still ok for Kefa.
The second line contains n integers a1, a2, ..., an,
where each ai either
equals to 0 (then vertex i has
no cat), or equals to 1 (then vertex i has
a cat).
Next n - 1 lines contains the edges of the tree in the format "xi yi"
(without the quotes) (1 ≤ xi, yi ≤ n, xi ≠ yi),
where xiand yi are
the vertices of the tree, connected by an edge.
It is guaranteed that the given set of edges specifies a tree.
Output
A single integer — the number of distinct leaves of a tree the path to which from Kefa's home contains at most mconsecutive vertices
with cats.
Sample test(s)
input
4 1 1 1 0 0 1 2 1 3 1 4
output
2
input
7 1
1 0 1 1 0 0 0
1 21 3
2 4
2 5
3 6
3 7
output
2
Note
Let us remind you that a tree is a connected graph on n vertices and n - 1 edge.
A rooted tree is a tree with a special vertex called root. In a rooted tree among any two vertices connected by an edge, one vertex
is a parent (the one closer to the root), and the other one is a child. A vertex is called a leaf, if it has no children.
Note to the first sample test:
The vertices containing cats are marked red. The restaurants
are at vertices 2, 3, 4. Kefa can't go only to the restaurant located at vertex 2.
Note to the second sample test:
The restaurants are located at vertices 4, 5, 6, 7. Kefa
can't go to restaurants 6, 7.
解题说明:此题是图论题,建一棵树,然后对树进行深度优先搜索题,由于一条路上不能连续出现k只猫,遍历路径时进行判断。如果走到了叶子那就得到了满足条件的一条路径。
#include<cstdio>
#include <cstring>
#include<iostream>
#include<algorithm>
#include<vector>
using namespace std;
int n,m,x,y,cnt,a[100005];
vector<int> b[100005];
void dfs(int p,int q,int pr)
{
int i,k,sz = b[p].size();
if(q > m)
{
return;
}
if(sz == 1 && p != 1)
{
cnt++;
return;
}
for(i=0; i<sz; i++)
{
k = b[p][i];
if(k == pr)
{
continue;
}
if(a[k])
{
dfs(k,q+1,p);
}
else
{
dfs(k,0,p);
}
}
}
int main()
{
int i;
cin>>n>>m;
for(i=1; i<=n; i++)
{
scanf("%d",&a[i]);
}
for(i=1; i<n; i++)
{
scanf("%d%d",&x,&y);
b[x].push_back(y);
b[y].push_back(x);
}
dfs(1,a[1],0);
cout<<cnt<<endl;
return 0;
}
相关文章推荐
- PMCAFF出品|十一月30篇爆款文章合集,干货、技能、内涵齐飞,总有一款适合你
- Django学习记录之Django 1.8 教程(我只是官网的搬运工)Tutorial Part 1
- ubuntu14.04 安装freeswich问题记录
- python 3 UDP小例子
- 人的不同目的
- HPU 1721: 感恩节KK专场——雪人的高度【线段树 离散化】
- $.each遍历json对象
- poj 1438--One-way Traffic(边的双连通)
- 茅山光大大团队第二次冲刺进度展示
- jsp servlet的区别和联系(转)
- spark 中的RDD编程 -以下基于Java api
- qmake配置版本
- JSP 技术 —— 是敌是友?
- Fast Compressive Tracking(快速压缩跟踪)算法的C++代码实现
- Html与CSS布局技巧
- jquery中怎么删除<ul>中的整个<li>包括节点
- 《需求分析与系统设计》第三篇阅读体会
- Spark中的wordCount程序实现
- Android StartActivityForResult两个Activity相互跳转传递消息
- IOS_Swift_enum枚举方法