BFS DFS(C++ )

/*

                      A
                    /    \
                  B       C
                /   \     /  \     
               D    E   F   G


深度優先遍歷(DFS) : A B D E C F G

廣度優先遍歷(BFS) : A B C D E F G

*/

TreeNode:

struct TreeNode {
	int val;
	TreeNode *left;
	TreeNode *right;
	TreeNode(int x) : val(x), left(NULL), right(NULL) {}
};
 

//深度優先遍歷(DFS)
void depthFirstSearch(TreeNode* root){
	stack<TreeNode *> nodeStack;  //使用C++的STL標準模板庫
	nodeStack.push(root);
	TreeNode *node;
	while (!nodeStack.empty()){
		node = nodeStack.top();
		cout << node->val;
		nodeStack.pop();
		if (node->right){
			nodeStack.push(node->right);  //先將右子樹壓棧
		}
		if (node->left){
			nodeStack.push(node->left);  //再將左子樹壓棧
		}
	}
}
 

//DFS 遞迴實現
void dfs(TreeNode* root)
{
	if (root){
		cout << root->val;
		dfs(root->left);
		dfs(root->right);
	}
}

//廣度優先遍歷(BFS)
void breadthFirstSearch(TreeNode* root){
	queue<TreeNode *> nodeQueue;  //使用C++的STL標準模板庫
	nodeQueue.push(root);
	TreeNode *node;
	while (!nodeQueue.empty()){
		node = nodeQueue.front();
		nodeQueue.pop();
		cout << node->val;
		if (node->left){
			nodeQueue.push(node->left);  //先將左子樹入隊
		}
		if (node->right){
			nodeQueue.push(node->right);  //再將右子樹入隊
		}
	}
}