剑指offer(22)—从上往下打印二叉树

从上往下打印二叉树

题目描述

思路

代码

/*
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) {
queue<TreeNode*> que;   //辅助队列
vector<int> vals;
if(root == NULL)
return vals;
que.push(root); //根节点入队列
while(!que.empty()){
TreeNode* pCur = que.front();
vals.push_back(pCur->val);  //输出根节点
que.pop();
if(pCur->left != NULL)  //若左子结点存在，则入队列
que.push(pCur->left);
if(pCur->right != NULL) //若右子结点存在，则入队列
que.push(pCur->right);
}
return vals;
}
};