title: LeetCode题解

LeetCode:Binary Tree Right Side View

date: 2016-10-09 20:09:12

[LeetCode,算法]

题目见Binary Tree Right Side View,从右侧观察树见到的树的第一个节点，从上到下输出出来，思路就是层序遍历，将每层的结点加入数组。具体代码见下：

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public List<Integer> rightSideView(TreeNode root) {
        List<Integer> res = new ArrayList<>();
        if(root == null) {
            return res;
        }
        List<TreeNode> nodelist = new ArrayList<>();
        nodelist.add(root);
        int cur = 0,last = nodelist.size();
        while(cur < nodelist.size()){
            last = nodelist.size();
            res.add(nodelist.get(last-1).val);
            for(;cur < last;cur++) {
                TreeNode temp = nodelist.get(cur);
                if(temp.left != null) {
                    nodelist.add(temp.left);
                } 
                if(temp.right != null) {
                    nodelist.add(temp.right);
                }
            }
        }
        return res;
    }
}