（C++）剑指offer-22：从上往下打印二叉树（举例让抽象具体化）

剑指offer-22：从上往下打印二叉树

目录

1题目描述

2题目解析

3题目答案

/*
struct TreeNode {
int val;
struct TreeNode *left;
struct TreeNode *right;
TreeNode(int x) :
val(x), left(NULL), right(NULL) {
}
};*/
class Solution {
public:
vector<int> PrintFromTopToBottom(TreeNode* root) {
vector<int> vec;
if(root==NULL) return vec;

queue<TreeNode*> TreeNodeQueue;
TreeNodeQueue.push(root);

while(!TreeNodeQueue.empty()){
TreeNode* TempNode = TreeNodeQueue.front();
TreeNodeQueue.pop();
vec.push_back(TempNode->val);

if(TempNode->left)  TreeNodeQueue.push(TempNode->left);
if(TempNode->right) TreeNodeQueue.push(TempNode->right);
}
return vec;
}
};

vector<int> PrintFromTopToBottom(TreeNode* root) {
vector<int> vec;
if(root==NULL) return vec;

queue<TreeNode*> q;
q.push(root);

while(!q.empty()){
TreeNode* t = q.front();
q.pop();
vec.push_back(t->val);

if(t->left)  q.push(t->left);
if(t->right) q.push(t->right);
}
return vec;
}