题目描述
从上到下按层打印二叉树,同一层结点从左至右输出。每一层输出一行。
/*
思路:用队列保存每一层的节点,完成层序遍历;
用end记录每层节点数目。
*/
/*
struct TreeNode {
int val;
struct TreeNode *left;
struct TreeNode *right;
TreeNode(int x) :
val(x), left(NULL), right(NULL) {
}
};
*/
class Solution {
public:
vector<vector<int> > Print(TreeNode* pRoot) {
vector<vector<int>> res;
if(pRoot==NULL)
return res;
queue<TreeNode*> q;
q.push(pRoot);
while(!q.empty()){
int start = 0,end = q.size();
vector<int> temp;
while(start < end){
TreeNode* node = q.front();
q.pop();
temp.push_back(node->val);
if(node->left!=NULL)
q.push(node->left);
if(node->right!=NULL)
q.push(node->right);
start++;
}
res.push_back(temp);
}
return res;
}
};