[LeetCode] Binary Tree Level Order Traversal
Given a binary tree, return the level order traversal of its nodes' values. (ie, from left to right, level by level).For example:
Given binary tree {3,9,20,#,#,15,7},
3
/ \
9 20
/ \
15 7
return its level order traversal as:
[
[3],
[9,20],
[15,7]
]
问题描述：给定一个二叉树，层次遍历它的所有节点。
class Solution {
public:
vector<vector<int> > levelOrder(TreeNode *root) {
// Note: The Solution object is instantiated only once and is reused by each test case.
if(root == NULL)
return vector<vector<int> >(0);
queue<pair<TreeNode *, int> > que;
vector<vector<int> > vec;
vector<int> ivec;
TreeNode *pnode = root;
int level = 0;
pair<TreeNode *, int> pair_data;
que.push(make_pair(pnode, 1));
while(!que.empty()) {
pair_data = que.front();
que.pop();
pnode = pair_data.first;
level = pair_data.second;
ivec.push_back(pnode->val);
if(que.empty() || level != que.front().second) {
vec.push_back(ivec);
ivec.clear();
}
if(pnode->left) {
que.push(make_pair(pnode->left, level+1));
}
if(pnode->right) {
que.push(make_pair(pnode->right, level+1));
}
}
return vec;
}
};
补充：软件开发 , C++ ,
