這篇文章小編將帶大家一起回顧經典C 之建構先序二叉樹，有興趣的小夥伴一起來複習一下吧！
二元樹首先要解決建構問題，才能考慮後續的遍歷，這裡貼出透過先序建構二元樹，同時包含四種二元樹的遍歷方法（先序，中序，後序，逐層）
第一、定義BinaryTreeNode 類別
#include #include #include using namespace std; templateclass BinaryTree; template class BinaryTreeNode { public: friend class BinaryTree; BinaryTreeNode() { data = NULL; lChild = rChild = NULL; } BinaryTreeNode(T newdata) { this->data = newdata; lChild = rChild = NULL; } T getData() { return data; } BinaryTreeNode * getLeftNode() { return lChild; } BinaryTreeNode * getRightNode() { return rChild; } T data; BinaryTreeNode* lChild; BinaryTreeNode* rChild; private: };
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第二、定義BinaryTree 類別
template class BinaryTree { public: BinaryTreeNode *root; char* p; BinaryTree() { root = NULL; } BinaryTree(T data) { root = new BinaryTreeNode(data); root->lChild = NULL; root->rChild = NULL; } ~BinaryTree() { delete root; } //构建二叉树并返回 BinaryTreeNode* CreateTree() { BinaryTreeNode* bt = NULL; char t; cin >> t; if (t == '#') { return NULL; } else { int num = t - '0'; bt = new BinaryTreeNode(num); bt->lChild = CreateTree(); bt->rChild = CreateTree(); } return bt; } //先序构建二叉树 BinaryTreeNode* PreCreateTree() { BinaryTreeNode* bt = NULL; if (this->root == NULL) { cout << "请输入根节点（#代表空树）:"; } else { cout << "请输入节点（#代表空树）:"; } char t; cin >> t; if (t == '#') { return NULL; } else { int num = t - '0'; bt = new BinaryTreeNode(num); if (this->root == NULL) { this->root = bt; } cout << bt->data << "的左孩子"; bt->lChild = PreCreateTree(); cout << bt->data << "的右边孩子"; bt->rChild = PreCreateTree(); } return bt; } void preOderTraversal(BinaryTreeNode *bt); //先序遍历 void inOrderTraversal(BinaryTreeNode *bt); //中序遍历 void postOrderTraversal(BinaryTreeNode *bt);//后序遍历 void levelTraversal(BinaryTreeNode *bt); //逐层遍历 private: }; template void BinaryTree::preOderTraversal(BinaryTreeNode *bt) { if (bt) { cout << bt->data; BinaryTree::preOderTraversal(bt->getLeftNode()); BinaryTree::preOderTraversal(bt->getRightNode()); } } template void BinaryTree::inOrderTraversal(BinaryTreeNode *bt) { if (bt) { BinaryTree::inOrderTraversal(bt->getLeftNode()); cout << bt->data; BinaryTree::inOrderTraversal(bt->getRightNode()); } } template void BinaryTree::postOrderTraversal(BinaryTreeNode *bt) { if (bt) { BinaryTree::postOrderTraversal(bt->getLeftNode()); BinaryTree::postOrderTraversal(bt->getRightNode()); cout << bt->data; } } template void BinaryTree::levelTraversal(BinaryTreeNode *bt) { queue*> que; que.push(bt); while (!que.empty()) { BinaryTreeNode* proot = que.front(); que.pop(); cout << proot->data; if (proot->lChild != NULL) { que.push(proot->lChild);//左孩子入队 } if (proot->rChild != NULL) { que.push(proot->rChild);//右孩子入队 } } }
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第三、主程式執行
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#include "pch.h" #include #include "BinaryTree.h" int main() { //场景测试2 BinaryTree btree; btree.PreCreateTree();//先序构建二叉树 cout << "先序遍历:"; btree.preOderTraversal(btree.root); cout << endl;//先序遍历 cout << "中序遍历:"; btree.inOrderTraversal(btree.root); cout << endl;//中序遍历 cout << "后序遍历:"; btree.postOrderTraversal(btree.root); cout << endl;//后序遍历 cout << "逐层序遍历:"; btree.levelTraversal(btree.root); }
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最終測試運行截圖
# 相關教學：C 影片教學
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