A1127 ZigZagging on a Tree [中序后序建树 自定义层序遍历]

实现这个自定义遍历的思路就是直接层序遍历存入一个数组，然后对这个数组自定义排序，然后输出就行了

#include<iostream>
#include<vector>
#include<map>
#include<string>
#include<cstring>
#include<cstdio>
#include<algorithm>
#include<set>
#include<queue>
using namespace std;
const int maxn = 30;
int post[maxn], in[maxn];
struct node
{
	int data, level, index;
	node* left, * right;
};

vector<node*>v;


bool cmp(node* a, node* b) {
	if (a->level != b->level) return a->level < b->level;
	if (a->level % 2 == 0) return a->index > b->index;
	return a->index < b->index;
}

node* create(int postl, int postr, int inl, int inr,int index,int level)
{
	if (postl > postr)
		return NULL;
	node* root = new node;
	root->data = post[postr];
	root->index = index;
	root->level = level;
	int i;
	for (i = inl; i <= inr; i++)
	{
		if (in[i] == post[postr])
			break;
	}
	int numleft = i - inl;
	root->left = create(postl, postl + numleft - 1, inl, i - 1,index*2+1,level+1);
	root->right = create(postl + numleft, postr - 1, i + 1, inr,index*2+2,level+1);
	return root;
}

void bfs(node *root)
{
	queue<node*>q;
	q.push(root);
	v.push_back(root);
	while (!q.empty())
	{
		node* now = q.front();
		q.pop();
		if (now->left!=NULL)
		{
			q.push(now->left);
			v.push_back(now->left);
		}
		if (now->right!=NULL) 
		{
			q.push(now->right);
			v.push_back(now->right);
		}
	}
}

int main()
{
	node* T; int n;
	cin >> n;
	for (int i = 0; i < n; i++)
		cin >> in[i];
	for (int i = 0; i < n; i++)
		cin >> post[i];
	T = create(0, n - 1, 0, n - 1,0,0);
	bfs(T);
	sort(v.begin(), v.end(), cmp);
	for (int i = 0; i < v.size(); i++) {
		if (i != 0) cout << " ";
		cout << v[i]->data;
	}
}

当然可以不用死套模板，更简洁的写法如下

#include<iostream>
#include<vector>
#include<map>
#include<string>
#include<cstring>
#include<cstdio>
#include<algorithm>
#include<set>
#include<queue>
using namespace std;
const int maxn = 30;
int post[maxn], in[maxn];
struct node
{
	int data, level, index;
	node* left, * right;
};

vector<node*>v;


bool cmp(node* a, node* b) {
	if (a->level != b->level) return a->level < b->level;
	if (a->level % 2 == 0) return a->index > b->index;
	return a->index < b->index;
}

void* create(int postl, int postr, int inl, int inr,int index,int level)
{
	if (postl > postr)
		return NULL;
	node* root = new node;
	root->data = post[postr];
	root->index = index;
	root->level = level;
	int i;
	for (i = inl; i <= inr; i++)
	{
		if (in[i] == post[postr])
			break;
	}
    v.push_back(root);
	int numleft = i - inl;
	create(postl, postl + numleft - 1, inl, i - 1,index*2+1,level+1);
	create(postl + numleft, postr - 1, i + 1, inr,index*2+2,level+1);
}

int main()
{
	node* T; int n;
	cin >> n;
	for (int i = 0; i < n; i++)
		cin >> in[i];
	for (int i = 0; i < n; i++)
		cin >> post[i];
	create(0, n - 1, 0, n - 1,0,0);
	sort(v.begin(), v.end(), cmp);
	for (int i = 0; i < v.size(); i++) {
		if (i != 0) cout << " ";
		cout << v[i]->data;
	}
}