PAT-A-1020. Tree Traversals (25)

1020. Tree Traversals (25)

时间限制

400 ms

内存限制

65536 kB

代码长度限制

16000 B

判题程序

Standard

作者

CHEN, Yue

Suppose that all the keys in a binary tree are distinct positive integers. Given the postorder and inorder traversal sequences, you are supposed to output the level order traversal sequence of the corresponding binary tree.

Input Specification:

Each input file contains one test case. For each case, the first line gives a positive integer N (<=30), the total number of nodes in the binary tree. The second line gives the postorder sequence and the third line gives the inorder sequence. All the numbers
in a line are separated by a space.

Output Specification:

For each test case, print in one line the level order traversal sequence of the corresponding binary tree. All the numbers in a line must be separated by exactly one space, and there must be no extra space at the end of the line.
Sample Input:

7
2 3 1 5 7 6 4
1 2 3 4 5 6 7

Sample Output:

4 1 6 3 5 7 2

#include<iostream>
#include<cstring>
#include<queue>
#include<algorithm>

using namespace std;

const int maxn = 50;

struct node{
int date;
node *lchild, *rchild;
};

int in[maxn], p
ca2f
ost[maxn];
int n;

node *create(int postl, int postr, int inl, int inr)
{
if (postl > postr)
return NULL;

node *root = new node;
root->date = post[postr];
int k;

for (k = inl; k <= inr; k++)
{
if (in[k] == post[postr])
break;
}

int len = k - inl;
root->lchild = create(postl, postl + len - 1, inl, k - 1);
root->rchild = create(postl + len, postr - 1, k + 1, inr);

return root;

}

int num = 0;
void layervisit(node *root)
{
queue<node *> q;
q.push(root);
while (!q.empty())
{
node *top = q.front();
q.pop();
num++;
cout << top->date;
if (num < n)
cout << " ";
if (top->lchild != NULL)
q.push(top->lchild);
if (top->rchild != NULL)
q.push(top->rchild);
}
}

int main()

{
cin >> n;
for (int i = 0; i < n; i++)
cin >> post[i];
for (int i = 0; i < n; i++)
cin >> in[i];

node *root = create(0, n - 1, 0, n - 1);
layervisit(root);

system("pause");
return 0;
}