二叉树

算法面试题/二叉搜索树.cpp

@@ -64,4 +64,70 @@ int
 	int max = 0, current = 0;
 	preorder(root, max, current);
 	return max;
+}
+
+vector<double> ¶þ²æËÑË÷Ê÷::averageOfLevels(TreeNode* root)
+{
+	vector<TreeNode*> vec{ root };
+	vector<double> ans;
+	while (!vec.empty() && vec.size() > 0) {
+		vector<TreeNode*> layerVec;
+		double value = 0;
+		for (int i = 0; i < vec.size(); i++) {
+			value += vec[i]->val;
+			if (vec[i]->left != nullptr)
+				layerVec.push_back(vec[i]->left);
+			if (vec[i]->right != nullptr)
+				layerVec.push_back(vec[i]->right);
+		}
+		if (vec.size() > 0)
+			ans.push_back(value / vec.size());
+		vec = layerVec;
+	}
+	return ans;
+}
+
+vector<int> ¶þ²æËÑË÷Ê÷::rightSideView(TreeNode* root) {
+	vector<TreeNode*> vec{ root };
+	vector<int> ans;
+	if (root == nullptr)
+		return ans;
+	while (!vec.empty() && vec.size() > 0) {
+		vector<TreeNode*> layerVec;
+		for (int i = 0; i < vec.size(); i++) {
+			if (vec[i]->right != nullptr)
+				layerVec.push_back(vec[i]->right);
+			if (vec[i]->left != nullptr)
+				layerVec.push_back(vec[i]->left);
+		}
+		if (vec.size() > 0)
+			ans.push_back(vec[0]->val);
+		vec = layerVec;
+	}
+	return ans;
+}
+
+vector<vector<int>> ¶þ²æËÑË÷Ê÷::zigzagLevelOrder(TreeNode* root) {
+	vector<TreeNode*> vec{ root };
+	vector<vector<int>> ans;
+	if (root == nullptr)
+		return ans;
+	int row = 0;
+	while (!vec.empty() && vec.size() > 0) {
+		vector<TreeNode*> layerVec;
+		vector<int> list;
+		for (int i = 0; i < vec.size(); i++) {
+			list.push_back(vec[i]->val);
+			if (vec[i]->right != nullptr)
+				layerVec.push_back(vec[i]->right);
+			if (vec[i]->left != nullptr)
+				layerVec.push_back(vec[i]->left);
+		}
+		if (row % 2 == 0)
+			reverse(list.begin(), list.end());
+		ans.push_back(list);
+		vec = layerVec;
+		row++;
+	}
+	return ans;
 }

算法面试题/二叉搜索树.h

@@ -1,4 +1,7 @@
 #pragma once
+#include <vector>
+using namespace std;
+
 struct TreeNode {
 	int val;
 	TreeNode* left;
@@ -15,5 +18,11 @@ public:
 	int getMinimumDifference(TreeNode* root);
 	// 104. 二叉树的最大深度
 	int maxDepth(TreeNode* root);
+	// 637. 二叉树的层平均值
+	vector<double> averageOfLevels(TreeNode* root);
+	// 199. 二叉树的右视图
+	vector<int> rightSideView(TreeNode* root);
+	// 103. 二叉树的锯齿形层序遍历
+	vector<vector<int>> zigzagLevelOrder(TreeNode* root);
 };