hdu
2016-04-14 23:51
239 查看
判断n个点是否构成一棵树的条件(无向):有n-1条边(每条边不同);
判断n个点是否构成一棵树的条件(有向):有n-1条边(每条边不同)且每个点的入度不能大于2;
Is It A Tree?
Description
A tree is a well-known data structure that is either empty (null, void, nothing) or is a set of one or more nodes connected by directed edges between nodes satisfying the following properties.
There is exactly one node, called the root, to which no directed edges point.
Every node except the root has exactly one edge pointing to it.
There is a unique sequence of directed edges from the root to each node.
For example, consider the illustrations below, in which nodes are represented by circles and edges are represented by lines with arrowheads. The first two of these are trees, but the last is not.
In this problem you will be given several descriptions of collections of nodes connected by directed edges. For each of these you are to determine if the collection satisfies the definition of a tree or not.
Input
The input will consist of a sequence of descriptions (test cases) followed by a pair of negative integers. Each test case will consist of a sequence of edge descriptions followed by a pair of zeroes Each edge description will consist of a pair of integers;
the first integer identifies the node from which the edge begins, and the second integer identifies the node to which the edge is directed. Node numbers will always be greater than zero.
Output
For each test case display the line "Case k is a tree." or the line "Case k is not a tree.", where k corresponds to the test case number (they are sequentially numbered starting with 1).
Sample Input
6 8 5 3 5 2 6 4
5 6 0 0
8 1 7 3 6 2 8 9 7 5
7 4 7 8 7 6 0 0
3 8 6 8 6 4
5 3 5 6 5 2 0 0
-1 -1
Sample Output
Case 1 is a tree.
Case 2 is a tree.
Case 3 is not a tree.
代码:
小希的迷宫
Description
上次Gardon的迷宫城堡小希玩了很久(见Problem B),现在她也想设计一个迷宫让Gardon来走。但是她设计迷宫的思路不一样,首先她认为所有的通道都应该是双向连通的,就是说如果有一个通道连通了房间A和B,那么既可以通过它从房间A走到房间B,也可以通过它从房间B走到房间A,为了提高难度,小希希望任意两个房间有且仅有一条路径可以相通(除非走了回头路)。小希现在把她的设计图给你,让你帮忙判断她的设计图是否符合她的设计思路。比如下面的例子,前两个是符合条件的,但是最后一个却有两种方法从5到达8。
Input
输入包含多组数据,每组数据是一个以0 0结尾的整数对列表,表示了一条通道连接的两个房间的编号。房间的编号至少为1,且不超过100000。每两组数据之间有一个空行。
整个文件以两个-1结尾。
Output
对于输入的每一组数据,输出仅包括一行。如果该迷宫符合小希的思路,那么输出"Yes",否则输出"No"。
Sample Input
6 8 5 3 5 2 6 4
5 6 0 0
8 1 7 3 6 2 8 9 7 5
7 4 7 8 7 6 0 0
3 8 6 8 6 4
5 3 5 6 5 2 0 0
-1 -1
Sample Output
Yes
Yes
No
代码:
判断n个点是否构成一棵树的条件(有向):有n-1条边(每条边不同)且每个点的入度不能大于2;
Is It A Tree?
Description
A tree is a well-known data structure that is either empty (null, void, nothing) or is a set of one or more nodes connected by directed edges between nodes satisfying the following properties.
There is exactly one node, called the root, to which no directed edges point.
Every node except the root has exactly one edge pointing to it.
There is a unique sequence of directed edges from the root to each node.
For example, consider the illustrations below, in which nodes are represented by circles and edges are represented by lines with arrowheads. The first two of these are trees, but the last is not.
In this problem you will be given several descriptions of collections of nodes connected by directed edges. For each of these you are to determine if the collection satisfies the definition of a tree or not.
Input
The input will consist of a sequence of descriptions (test cases) followed by a pair of negative integers. Each test case will consist of a sequence of edge descriptions followed by a pair of zeroes Each edge description will consist of a pair of integers;
the first integer identifies the node from which the edge begins, and the second integer identifies the node to which the edge is directed. Node numbers will always be greater than zero.
Output
For each test case display the line "Case k is a tree." or the line "Case k is not a tree.", where k corresponds to the test case number (they are sequentially numbered starting with 1).
Sample Input
6 8 5 3 5 2 6 4
5 6 0 0
8 1 7 3 6 2 8 9 7 5
7 4 7 8 7 6 0 0
3 8 6 8 6 4
5 3 5 6 5 2 0 0
-1 -1
Sample Output
Case 1 is a tree.
Case 2 is a tree.
Case 3 is not a tree.
代码:
#include <iostream> #include <cstring> #include <algorithm> using namespace std; int pre[100005],dis[100005],In[1000005]; void cmp() { memset(In,0,sizeof(In)); memset(dis,0,sizeof(dis)); for(int i=1;i<=100000;i++) pre[i]=i; } int find(int x) { while(x!=pre[x]) x=pre[x]; return x; } int main() { int i,j,k,m,n,p,q=1,flag,ok; while(1) { cmp(); flag=0;k=0;ok=0;p=0; while(cin>>n>>m) { if(n<0&&m<0) { flag=1; break; } if(n==0&&m==0) break; int fx=find(n); int fy=find(m); if(fx!=fy) { pre[fx]=fy;p++; In[m]++; if(In[m]>=2) ok=1;//入度不能大2 } else ok=1; if(dis ==0) k++; if(dis[m]==0) k++; dis =dis[m]=1; } if(flag) break; if(ok==0) { if(k-1!=p) ok=1; if(p==0&&k==0) ok=0; } cout<<"Case "<<q++; if(ok) cout<<" is not a tree."<<endl; else cout<<" is a tree."<<endl; } return 0; }
小希的迷宫
Description
上次Gardon的迷宫城堡小希玩了很久(见Problem B),现在她也想设计一个迷宫让Gardon来走。但是她设计迷宫的思路不一样,首先她认为所有的通道都应该是双向连通的,就是说如果有一个通道连通了房间A和B,那么既可以通过它从房间A走到房间B,也可以通过它从房间B走到房间A,为了提高难度,小希希望任意两个房间有且仅有一条路径可以相通(除非走了回头路)。小希现在把她的设计图给你,让你帮忙判断她的设计图是否符合她的设计思路。比如下面的例子,前两个是符合条件的,但是最后一个却有两种方法从5到达8。
Input
输入包含多组数据,每组数据是一个以0 0结尾的整数对列表,表示了一条通道连接的两个房间的编号。房间的编号至少为1,且不超过100000。每两组数据之间有一个空行。
整个文件以两个-1结尾。
Output
对于输入的每一组数据,输出仅包括一行。如果该迷宫符合小希的思路,那么输出"Yes",否则输出"No"。
Sample Input
6 8 5 3 5 2 6 4
5 6 0 0
8 1 7 3 6 2 8 9 7 5
7 4 7 8 7 6 0 0
3 8 6 8 6 4
5 3 5 6 5 2 0 0
-1 -1
Sample Output
Yes
Yes
No
代码:
#include <iostream> #include <cstring> #include <algorithm> using namespace std; int pre[100005],dis[100005]; void cmp() { memset(dis,0,sizeof(dis)); for(int i=1;i<=100000;i++) pre[i]=i; } int find(int x) { while(x!=pre[x]) x=pre[x]; return x; } int main() { int i,j,k,m,n,p,q,flag,ok; while(1) { cmp(); flag=0;k=0;ok=0;p=0; while(cin>>n>>m) { if(n==-1&&m==-1) { flag=1; break; } if(n==0&&m==0) break; int fx=find(n); int fy=find(m); if(fx!=fy) { pre[fx]=fy;p++; } else ok=1; if(dis ==0) k++; if(dis[m]==0) k++; dis =dis[m]=1; } if(flag) break; if(ok==0) { if(k-1!=p) ok=1; if(p==0&&k==0) ok=0; } if(ok) cout<<"No"<<endl; else cout<<"Yes"<<endl; } return 0; }
相关文章推荐
- 如何在筛选后的表里复制粘贴数据到同行的操作
- java 简易计算器Swing
- maven入门
- XMLHttpRequest statu 4000 s = 0
- 【POJ 2796】 Feel Good
- LeetCode-38. Count and Say
- 【BZOJ1069】【SCOI2007】最大土地面积 计算几何 凸包
- java--正则表达式——邮箱规范
- 写日报
- linux脚本编程之条件判断
- 20145240 《Java程序设计》第二次实验报告
- mysql中表名是order的CRUD的错误
- 实例 20 重定向输出流实现程序日志
- Akka在Flink中的使用剖析
- 故障案例--mongodb添加副本集成员报错
- ASP.NET MVC之分部视图和ChildAction(三)
- JavaScript函数劫持
- Android中Service类onStartCommand
- poj 1419 dfs
- 括号匹配