二叉树的遍历——还原二叉树

#include<stdio.h>
#include<queue>
using namespace std;
const int maxn = 50;
struct node{
    
    
	int data;
	node* lchild;
	node* rchild;
};

int post[maxn], in[maxn];
int n;

node* create(int postL, int postR, int inL, int inR)
{
    
    
	if(postL > postR) return NULL;
	node* root = new node;
	root->data = post[postR];
	int k;
	for(k = inL; k <= inR; k++)
	{
    
    
		if(in[k] == post[postR])
		    break;
	}
	int numLeft = k - inL;
	root->lchild = create(postL, postL + numLeft - 1, inL, k - 1);
	root->rchild = create(postL + numLeft, postR - 1, k + 1, inR);
	return root;
}

int num = 0;
void BFS(node* root)
{
    
    
	queue<node*> Q;
	Q.push(root);
	while(!Q.empty())
	{
    
    
		node* now = Q.front();
		Q.pop();
		printf("%d", now->data);
		num++;
		if(num < n) printf(" ");
		if(now->lchild != NULL) Q.push(now->lchild);
		if(now->rchild != NULL) Q.push(now->rchild);
	}
}

int main()
{
    
    
	scanf("%d", &n);
	for(int i = 0; i < n; i++)
	{
    
    
		scanf("%d", &post[i]);
	}
	for(int i = 0; i < n; i++)
	{
    
    
		scanf("%d", &in[i]);
	}
	node* root = create(0, n - 1, 0, n - 1);
	BFS(root);
	return 0;
}