从上往下打印二叉树

[guanpengchn]

题目描述

从上往下打印出二叉树的每个节点，同层节点从左至右打印。

/*
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*> q;
        q.push(root);
        vector<int> result;
        if(!root){
            return result;
        }
        while(!q.empty()){
            root = q.front();
            q.pop();
            result.push_back(root->val);
            if(root->left){
                q.push(root->left);
            }
            if(root->right){
                q.push(root->right);
            }
        }
        return result;
    }
};