【PAT】1020 Tree Traversals (25) [tree][traversal]

1020 Tree Traversals (25分)
后序+中序转层序
node保存结点标号，按标号升序输出

//#define _CRT_SECURE_NO_WARNINGS
#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;

struct node
{
	int id;//按完全二叉树的下标
	int val;//值
};

bool cmp(node a, node b)
{
	return a.id < b.id;
}

vector<int> post, in;// postorder sequence// inorder sequence
vector<node> tree;

void preOrder(int root,int start,int end,int id)
{
	if (start > end)return;
	int index = start;
	while (in[index] != post[root])index++;
	tree.push_back({id,post[root]});//根
	preOrder(root - end + index - 1,start, index - 1, 2 * id + 1);//左//id从0开始
	preOrder(root - 1, index + 1, end, 2 * id + 2);//右
	return;
}

int main()
{
	//freopen("input.txt", "r", stdin);
	int n;
	cin >> n;
	post.resize(n);
	in.resize(n);
	for (int i = 0; i < n; i++)
		cin >> post[i];
	for (int i = 0; i < n; i++)
		cin >> in[i];
	preOrder(n - 1, 0, n - 1,0);
	sort(tree.begin(),tree.end(),cmp);//按下标输出
	cout << tree[0].val;
	for (int i = 1; i < tree.size(); i++)
		cout << " "<<tree[i].val;
	return 0;
}