首页 > 代码库 > Binary Tree Zigzag Level Order Traversal
Binary Tree Zigzag Level Order Traversal
Given a binary tree, return the zigzag level order traversal of its nodes‘ values. (ie, from left to right, then right to left for the next level and alternate between).
For example:
Given binary tree {3,9,20,#,#,15,7},
3 / 9 20 / 15 7
return its zigzag level order traversal as:
[ [3], [20,9], [15,7]]
C++实现如下：
#include<iostream>#include<new>#include<vector>#include<stack>using namespace std;//Definition for binary treestruct TreeNode{ int val; TreeNode *left; TreeNode *right; TreeNode(int x) : val(x), left(NULL), right(NULL) {}};class Solution{public: vector<vector<int> > zigzagLevelOrder(TreeNode *root) { stack<int> st; vector<vector<int> > vec;//用来存放每一层的关键字 vector<vector<TreeNode*> > rvec; //用来存放每一层的结点 size_t i=0; if(root==NULL) return vector<vector<int> >(); vec.push_back({root->val}); rvec.push_back({root}); vector<int> v1; //用来存放一层的关键字 vector<TreeNode*> v2; //用来存放一层的结点 int flag=0;//控制是正序还是逆序打印该层的元素 while(rvec.size()) { v1.clear(); v2.clear(); if(flag==0) { //每次只对最后一层进行操作 for(i=0; i<rvec[rvec.size()-1].size(); i++) { TreeNode *tmp=rvec[rvec.size()-1][i]; if(tmp->left) { st.push(tmp->left->val); v2.push_back(tmp->left); } if(tmp->right) { st.push(tmp->right->val); v2.push_back(tmp->right); } } while(!st.empty()) { v1.push_back(st.top()); st.pop(); } if(!v1.empty()&&!v2.empty()) { vec.push_back(v1); rvec.push_back(v2); } else break; flag=1; } else { for(i=0; i<rvec[rvec.size()-1].size(); i++) { TreeNode *tmp=rvec[rvec.size()-1][i]; if(tmp->left) { v1.push_back(tmp->left->val); v2.push_back(tmp->left); } if(tmp->right) { v1.push_back(tmp->right->val); v2.push_back(tmp->right); } } if(!v1.empty()&&!v2.empty()) { vec.push_back(v1); rvec.push_back(v2); } else break; flag=0; } } return vec; } void createTree(TreeNode *&root) { int i; cin>>i; if(i!=0) { root=new TreeNode(i); if(root==NULL) return; createTree(root->left); createTree(root->right); } }};int main(){ Solution s; TreeNode *root; s.createTree(root); vector<vector<int> > vec=s.zigzagLevelOrder(root); for(auto a:vec) { for(auto v:a) cout<<v<<" "; cout<<endl; }}
运行结果：
Binary Tree Zigzag Level Order Traversal
声明：以上内容来自用户投稿及互联网公开渠道收集整理发布，本网站不拥有所有权，未作人工编辑处理，也不承担相关法律责任，若内容有误或涉及侵权可进行投诉： 投诉/举报 工作人员会在5个工作日内联系你，一经查实，本站将立刻删除涉嫌侵权内容。