Given a binary tree, imagine yourself standing on the right side of it, return the values of the nodes you can see ordered from top to bottom.
For example:
Given the following binary tree,
1 <--- / \ 2 3 <--- \ \ 5 4 <---
You should return [1, 3, 4]
.
Solutions:
易想到求的是每層中最右的一個節點。
二叉樹層序遍歷過程中,每次循環開始時,隊列中存放的剛好是將要訪問的一層的節點。
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
vector<int> rightSideView(TreeNode* root) {
vector<int> result;
if(root==NULL){
return result;
}
queue<TreeNode*> Q;
Q.push(root);
TreeNode *right;
while(!Q.empty()) {
int Qsize=Q.size();
for(int i=0; i<Qsize; ++i) {
right=Q.front();
Q.pop();
if(right->left != NULL){
Q.push(right->left);
}
if(right->right != NULL){
Q.push(right->right);
}
}
result.push_back(right->val);
}
}
};