1004. Counting Leaves(30分)
A family hierarchy is usually presented by a pedigree tree. Your job is to count those family members who have no child.
Input Specification:
Each input file contains one test case. Each case starts with a line containing 0<N<100, the number of nodes in a tree, and M (<N), the number of . Then M lines follow, each in the format:
ID K ID[1] ID[2] ... ID[K]
where
ID
is a two-digit number representing a given non-leaf node,K
is the number of its children, followed by a sequence of two-digitID
's of its children. For the sake of simplicity, let us fix the root ID to be01
.The input ends with N being 0. That case must NOT be processed.
Output Specification:
For each test case, you are supposed to count those family members who have no child for every seniority level starting from the root. The numbers must be printed in a line, separated by a space, and there must be no extra space at the end of each line.
The sample case represents a tree with only 2 nodes, where
01
is the root and02
is its only child. Hence on the root01
level, there is0
leaf node; and on the next level, there is1
leaf node. Then we should output0 1
in a line.Sample Input:
2 1 01 1 02 结尾无空行
Sample Output:
0 1 结尾无空行
#include <iostream>
#include <vector>
using namespace std;
int maxlevel = 1;
int leaf[100] = {
0};
vector<int> P[100];
void DFS(int parent, int level)
{
maxlevel = max(maxlevel, level);
// 如果该点没有孩子结点
if (!P[parent].size())
{
leaf[level]++;
return;
}
// 依次搜索该点的每一个孩子结点
for (int i = 0; i < P[parent].size(); i++)
{
DFS(P[parent][i], level + 1);
}
}
int main()
{
int N, M;
cin >> N >> M;
for (int i = 0; i < M; i++)
{
int parent, k, id;
cin >> parent >> k;
for (int j = 0; j < k; j++)
{
cin >> id;
P[parent].push_back(id);
}
}
DFS(1, 1);
cout << leaf[1];
for (int i = 2; i <= maxlevel; i++)
{
cout << " " << leaf[i];
}
return 0;
}
简单的深度优先搜索,需要注意的是数组存放孩子节点。每次递归要更新树的最大深度。