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traverse.h
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executable file
·282 lines (260 loc) · 7.72 KB
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/*
@filename traverse.cpp
@author caonan
@date 2022-04-13 23:39:37
@reference
@url
@brief 二叉树基本遍历练习
*/
#ifndef _TRAVERSE_H_
#define _TRAVERSE_H_
#include <assert.h>
#include <stdio.h>
#include <algorithm>
#include <iostream>
#include <map>
#include <queue>
#include <stack>
#include <vector>
using namespace std;
namespace tree_util
{
struct TreeNode {
int val;
TreeNode* left;
TreeNode* right;
TreeNode() : val(0), left(nullptr), right(nullptr) {}
TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
TreeNode(int x, TreeNode* left, TreeNode* right) : val(x), left(left), right(right) {}
};
//这里先只以节点val为int类型的二叉树为例子,按照遍历顺序输出arr数组
class Traversal
{
public:
enum TraverseType {
inorder,
preorder,
postorder,
inorderNoneRecursion,
preorderNoneRecursion,
postorderNoneRecursion,
bfs
};
// default create increasing complete binary tree
explicit Traversal(int node_count, int begin = 0)
{
assert(node_count >= 0);
if (!node_count) return;
root_ = new TreeNode(begin);
queue<TreeNode*> tree_queue;
tree_queue.push(root_);
for (int i = begin + 1; i < begin + node_count; i += 2) {
auto node = tree_queue.front();
node->left = new TreeNode(i);
tree_queue.push(node->left);
if (i + 1 < begin + node_count) {
node->right = new TreeNode(i + 1);
tree_queue.push(node->right);
}
tree_queue.pop();
}
}
// preorder string ,null with'#' number split with ','
//example:10,9,##20,15,##7,
explicit Traversal(const std::string s)
{
int i = 0;
root_ = dfs(s, i);
}
~Traversal()
{
if (!root_) return;
queue<TreeNode*> tree_queue;
tree_queue.push(root_);
while (!tree_queue.empty()) {
auto node = tree_queue.front();
if (node->left) tree_queue.push(node->left);
if (node->right) tree_queue.push(node->right);
delete node;
tree_queue.pop();
}
}
void set_search_balance(){
}
void show_graph_current_tree(TreeNode* head = nullptr)
{
cout << "----------show_graph_current_tree----------" << endl;
if (!head) head = root_;
queue<TreeNode*> tree_queue;
tree_queue.push(head);
while (!tree_queue.empty()) {
int size = tree_queue.size();
while (size-- > 0) {
auto node = tree_queue.front();
cout << node->val << " ";
if (node->left) tree_queue.push(node->left);
if (node->right) tree_queue.push(node->right);
tree_queue.pop();
}
cout << endl;
}
}
void show_val_order(TraverseType type = bfs)
{
auto printList = [](const vector<int>& arr) {
for (auto v : arr) cout << v << " ";
cout << endl;
};
vector<int> ans;
switch (type) {
case inorder: {
cout << "----------inorderTraversalRecursion----------" << endl;
ans = inorderTraversalRecursion();
} break;
case preorder: {
cout << "----------preorderTraversalRecursion----------" << endl;
ans = preorderTraversalRecursion();
} break;
case postorder: {
cout << "----------postorderTraversalRecursion----------" << endl;
ans = postorderTraversalRecursion();
} break;
case inorderNoneRecursion: {
cout << "----------inorderTraversal----------" << endl;
ans = inorderTraversal();
} break;
case preorderNoneRecursion: {
cout << "----------preorderTraversal----------" << endl;
ans = preorderTraversal();
} break;
case postorderNoneRecursion: {
cout << "----------postorderTraversal----------" << endl;
ans = postorderTraversal();
} break;
case bfs: {
cout << "----------bfsTraversal----------" << endl;
ans = bfsTraversal();
} break;
default:
break;
}
printList(ans);
}
//广度遍历
vector<int> bfsTraversal()
{
vector<int> ans;
auto head = root_;
if (!head) return ans;
queue<TreeNode*> tree_queue;
tree_queue.push(head);
while (!tree_queue.empty()) {
auto node = tree_queue.front();
ans.push_back(node->val);
if (node->left) tree_queue.push(node->left);
if (node->right) tree_queue.push(node->right);
tree_queue.pop();
}
return ans;
}
//中序
vector<int> inorderTraversalRecursion()
{
vector<int> ans;
auto head = root_;
dfs(head, ans, inorder);
return ans;
}
//前序
vector<int> preorderTraversalRecursion()
{
vector<int> ans;
auto head = root_;
dfs(head, ans, preorder);
return ans;
}
//后序
vector<int> postorderTraversalRecursion()
{
vector<int> ans;
auto head = root_;
dfs(head, ans, postorder);
return ans;
}
//中序非递归
vector<int> inorderTraversal(TraverseType type = inorderNoneRecursion)
{
vector<int> ans;
auto cur_node = root_;
stack<TreeNode*> tree_stack;
while (cur_node || !tree_stack.empty()) {
while (cur_node) {
if (type == preorderNoneRecursion) ans.push_back(cur_node->val);
tree_stack.push(cur_node);
cur_node = cur_node->left;
}
cur_node = tree_stack.top();
if (type == inorderNoneRecursion) ans.push_back(cur_node->val);
cur_node = cur_node->right;
tree_stack.pop();
}
return ans;
}
//前序非递归
vector<int> preorderTraversal() { return inorderTraversal(preorderNoneRecursion); }
//后序非递归
vector<int> postorderTraversal()
{
vector<int> ans;
auto cur_node = root_;
decltype(cur_node) pre_node = nullptr;
stack<TreeNode*> tree_stack;
while (cur_node || !tree_stack.empty()) {
while (cur_node) {
tree_stack.push(cur_node);
cur_node = cur_node->left;
}
cur_node = tree_stack.top();
if (cur_node->right && cur_node->right != pre_node) {
cur_node = cur_node->right;
} else {
ans.push_back(cur_node->val);
pre_node = cur_node;
cur_node = nullptr;
tree_stack.pop();
}
}
return ans;
}
TreeNode* getRoot() { return root_; }
private:
void dfs(TreeNode* node, vector<int>& ans_arr, TraverseType type)
{
if (node) {
if (type == preorder) ans_arr.push_back(node->val);
dfs(node->left, ans_arr, type);
if (type == inorder) ans_arr.push_back(node->val);
dfs(node->right, ans_arr, type);
if (type == postorder) ans_arr.push_back(node->val);
}
}
TreeNode* dfs(const string& s, int& i)
{
if (s[i] == '#') {
++i;
return nullptr;
}
int len = i;
while (s[len++] != ',');
int inum = stoi(s.substr(i, len - i - 1));
i = len;
TreeNode* root = new TreeNode(inum);
root->left = dfs(s, i);
root->right = dfs(s, i);
return root;
}
private:
TreeNode* root_{nullptr};
};
} // namespace tree_util
#endif