[백준/c++] 1991: 트리 순회

https://www.acmicpc.net/problem/1991

정답 코드1

#include <iostream>
#include <vector>
using namespace std;
class BinaryNode {
public:
	char data;
	BinaryNode* left;
	BinaryNode* right;
	BinaryNode(char val = ' ', BinaryNode* l = NULL, BinaryNode* r = NULL)
		:data(val), left(l), right(r){}
	~BinaryNode(){}
	void setData(char val) {
		data = val;
	}
	char getData() {
		return data;
	}
	void setLeft(BinaryNode* l) {
		left = l;
	}
	BinaryNode* getLeft() {
		return left;
	}
	void setRight(BinaryNode* r) {
		right = r;
	}
	BinaryNode* getRight() {
		return right;
	}
};
class BinaryTree {
	BinaryNode* root;
public:
	BinaryTree()
		:root(NULL){}
	~BinaryTree(){}
	void setRoot(BinaryNode* n) {
		root = n;
	}
	BinaryNode* getRoot() {
		return root;
	}
	void preorder(BinaryNode* node) {
		if (node != NULL) {
			cout << node->getData();
			if (node->getLeft() != NULL) preorder(node->getLeft());
			if (node->getRight() != NULL) preorder(node->getRight());
		}
	}
	void inorder(BinaryNode* node) {
		if (node != NULL) {
			if (node->getLeft() != NULL) inorder(node->getLeft());
			cout << node->getData();
			if (node->getRight() != NULL) inorder(node->getRight());
		}
	}
	void postorder(BinaryNode* node) {
		if (node != NULL) {
			if (node->getLeft() != NULL) postorder(node->getLeft());
			if (node->getRight() != NULL) postorder(node->getRight());
			cout << node->getData();
		}
	}
};
int main() {
	int N;
	cin >> N;
	vector<BinaryNode*> node;
	node.resize(N);
	// BinaryNode 생성
	for (int i = 0;i < N;i++) {
		node[i] = new BinaryNode('A' + i);
	}
	// 노드 간 링크 연결
	for (int i = 0;i < N;i++) {
		char p, left, right;
		cin >> p >> left >> right;
		if (left != '.') node[p - 'A']->setLeft(node[left - 'A']);
		if (right != '.') node[p - 'A']->setRight(node[right - 'A']);
	}
	// BinaryTree 생성
	BinaryTree* tree = new BinaryTree();
	tree->setRoot(node[0]); // BinaryNode* 자료형을 setRoot()에 넣어야하므로 'A'라고 넣으면 에러 발생한다
	tree->preorder(tree->getRoot());
	cout << endl;
	tree->inorder(tree->getRoot());
	cout << endl;
	tree->postorder(tree->getRoot());
	return 0;
}

위의 코드로 해결했지만 굳이 tree를 포인터로 구현해야 했을까?라는 생각이 들어서 포인터를 사용하지 않고 구현하기로 결심하고 두 번째 코드를 구현했다

정답코드2

#include <iostream>
#include <vector>
using namespace std;
class BinaryNode {
public:
	char data;
	BinaryNode* left;
	BinaryNode* right;
	BinaryNode(char val=' ',BinaryNode* l=NULL,BinaryNode* r=NULL)
		:data(val),right(r),left(l){}
	~BinaryNode(){}
	void setData(char n) {
		data = n;
	}
	char getData() {
		return data;
	}
	void setLeft(BinaryNode* l) {
		left = l;
	}
	BinaryNode* getLeft() {
		return left;
	}
	void setRight(BinaryNode* l) {
		right = l;
	}
	BinaryNode* getRight() {
		return right;
	}
};
class BinaryTree {
	BinaryNode* root;
public:
	BinaryTree()
		:root(NULL){}
	~BinaryTree(){}
	void setRoot(BinaryNode* n) {
		root = n;
	}
	BinaryNode* getRoot() {
		return root;
	}
	void inorder(BinaryNode* node) {
		if (node != NULL) {
			if (node->getLeft() != NULL) inorder(node->getLeft());
			cout << node->getData();
			if (node->getRight() != NULL) inorder(node->getRight());
		}
	}
	void preorder(BinaryNode* node) {
		if (node != NULL) {
			cout << node->getData();
			if (node->getLeft() != NULL) preorder(node->getLeft());
			if (node->getRight() != NULL) preorder(node->getRight());
		}
	}
	void postorder(BinaryNode* node) {
		if (node != NULL) {
			if (node->getLeft() != NULL) postorder(node->getLeft());
			if (node->getRight() != NULL) postorder(node->getRight());
			cout << node->getData();
		}
	}
};
int main() {
	int N;
	cin >> N;
	vector<BinaryNode*> node;
	node.resize(N);
	// BinaryNode 생성
	for (int i = 0;i < N;i++) {
		node[i] = new BinaryNode('A' + i);
	}
	for (int i = 0;i < N;i++) {
		char p, left, right;
		cin >> p >> left >> right;
		if (left != '.') node[p - 'A']->setLeft(node[left - 'A']);
		if (right != '.') node[p - 'A']->setRight(node[right - 'A']);
	}

	BinaryTree tree;
	tree.setRoot(node[0]);
	tree.preorder(tree.getRoot());
	cout << endl;
	tree.inorder(tree.getRoot());
	cout << endl;
	tree.postorder(tree.getRoot());
	return 0;
}