POJ 1330 大一暑假ACM集训
2015-08-25 11:58
260 查看
Description
A rooted tree is a well-known data structure in computer science and engineering. An example is shown below:
In the figure, each node is labeled with an integer from {1, 2,...,16}. Node 8 is the root of the tree. Node x is an ancestor of node y if node x is in the path between the root and node y. For example, node 4 is an ancestor of node 16. Node 10 is also an ancestor
of node 16. As a matter of fact, nodes 8, 4, 10, and 16 are the ancestors of node 16. Remember that a node is an ancestor of itself. Nodes 8, 4, 6, and 7 are the ancestors of node 7. A node x is called a common ancestor of two different nodes y and z if node
x is an ancestor of node y and an ancestor of node z. Thus, nodes 8 and 4 are the common ancestors of nodes 16 and 7. A node x is called the nearest common ancestor of nodes y and z if x is a common ancestor of y and z and nearest to y and z among their common
ancestors. Hence, the nearest common ancestor of nodes 16 and 7 is node 4. Node 4 is nearer to nodes 16 and 7 than node 8 is.
For other examples, the nearest common ancestor of nodes 2 and 3 is node 10, the nearest common ancestor of nodes 6 and 13 is node 8, and the nearest common ancestor of nodes 4 and 12 is node 4. In the last example, if y is an ancestor of z, then the nearest
common ancestor of y and z is y.
Write a program that finds the nearest common ancestor of two distinct nodes in a tree.
Input
The input consists of T test cases. The number of test cases (T) is given in the first line of the input file. Each test case starts with a line containing an integer N , the number of nodes in a tree, 2<=N<=10,000. The nodes are labeled with integers 1, 2,...,
N. Each of the next N -1 lines contains a pair of integers that represent an edge --the first integer is the parent node of the second integer. Note that a tree with N nodes has exactly N - 1 edges. The last line of each test case contains two distinct integers
whose nearest common ancestor is to be computed.
Output
Print exactly one line for each test case. The line should contain the integer that is the nearest common ancestor.
Sample Input
Sample Output
代码
A rooted tree is a well-known data structure in computer science and engineering. An example is shown below:
In the figure, each node is labeled with an integer from {1, 2,...,16}. Node 8 is the root of the tree. Node x is an ancestor of node y if node x is in the path between the root and node y. For example, node 4 is an ancestor of node 16. Node 10 is also an ancestor
of node 16. As a matter of fact, nodes 8, 4, 10, and 16 are the ancestors of node 16. Remember that a node is an ancestor of itself. Nodes 8, 4, 6, and 7 are the ancestors of node 7. A node x is called a common ancestor of two different nodes y and z if node
x is an ancestor of node y and an ancestor of node z. Thus, nodes 8 and 4 are the common ancestors of nodes 16 and 7. A node x is called the nearest common ancestor of nodes y and z if x is a common ancestor of y and z and nearest to y and z among their common
ancestors. Hence, the nearest common ancestor of nodes 16 and 7 is node 4. Node 4 is nearer to nodes 16 and 7 than node 8 is.
For other examples, the nearest common ancestor of nodes 2 and 3 is node 10, the nearest common ancestor of nodes 6 and 13 is node 8, and the nearest common ancestor of nodes 4 and 12 is node 4. In the last example, if y is an ancestor of z, then the nearest
common ancestor of y and z is y.
Write a program that finds the nearest common ancestor of two distinct nodes in a tree.
Input
The input consists of T test cases. The number of test cases (T) is given in the first line of the input file. Each test case starts with a line containing an integer N , the number of nodes in a tree, 2<=N<=10,000. The nodes are labeled with integers 1, 2,...,
N. Each of the next N -1 lines contains a pair of integers that represent an edge --the first integer is the parent node of the second integer. Note that a tree with N nodes has exactly N - 1 edges. The last line of each test case contains two distinct integers
whose nearest common ancestor is to be computed.
Output
Print exactly one line for each test case. The line should contain the integer that is the nearest common ancestor.
Sample Input
2 16 1 14 8 5 10 16 5 9 4 6 8 4 4 10 1 13 6 15 10 11 6 7 10 2 16 3 8 1 16 12 16 7 5 2 3 3 4 3 1 1 5 3 5
Sample Output
4 3
代码
#include <iostream> #include <vector> using namespace std; const int N =10000; vector<int> a ; int f ,r ; void DFS(int u,int dep) { r[u]=dep; for (vector<int>::iterator it =a[u].begin(); it!=a[u].end(); ++it) DFS(*it,dep+1); } int main() { int casenum,num,n,i,x,y; scanf("%d",&casenum); for (num=0; num<casenum; num++) { scanf("%d",&n); for (i=0; i<n; i++) a[i].clear(); memset(f,255,sizeof(f)); for(i=0; i<n-1; i++) { scanf ("%d %d",&x,&y); a[x-1].push_back(y-1); f[y-1]=x-1; } for (i=0; f[i]>=0; i++); DFS(i,0); scanf("%d %d",&x,&y); x--; y--; while (x!=y) { if (r[x]>r[y])x=f[x]; else y=f[y]; } printf("%d\n",x+1); } return 0; }
相关文章推荐
- 朴素贝叶斯分类
- mysql索引操作(增删查)
- 习近平的民族观
- 图形界面还是命令窗口
- STL学习----入门(2)[组件]
- DIY家庭收支记账工具,如何正确的成为一名妻管严
- 微信公众平台开发【素材管理】获取临时素材
- halcon学习笔记——(4)HDevelop language(结构语句)
- 如何在Ubuntu手机中实现Contact importer
- PCA的数学原理
- Partition List
- Ionic 实现双击返回键退出功能
- 对百度地图SDK中的真机framework和模拟器framework合并时遇到的问题,sdkframework
- 关于linux的历史
- 给设计师的品牌故事设计指南
- 关于Qt5 使用QQuickWidget加载QML背景设置透明的问题!
- Android-ScrollView(基本实现,顶部判断,底部判断,底部加载更多)
- 网站所有超链接都在新窗口打开
- Rational Rose 2007
- Android下SQLite数据库学习笔记2——Android下SQL语句实现数据库的增删改查