二叉树篇
tql
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode() {}
* TreeNode(int val) { this.val = val; }
* TreeNode(int val, TreeNode left, TreeNode right) {
* this.val = val;
* this.left = left;
* this.right = right;
* }
* }
*/
class Solution {
public List<Integer> rightSideView(TreeNode root) {
List<Integer> ret=new ArrayList<>();
dfs(root,0,ret);
return ret;
}
private void dfs(TreeNode root,int depth,List<Integer>ret){
if(root==null){
return;
}
//这个深度首次达到
if(depth==ret.size()){
ret.add(root.val);
}
//先递归右子树，再递归左子树
dfs(root.right,depth+1,ret);
dfs(root.left,depth+1,ret);
}
}