【leetcode】199.(Medium) Binary Tree Right Side View
解题思路:
用两个链表row1和row2分别记录每一层的节点
提交代码:
class Solution {
public List<Integer> rightSideView(TreeNode root) {
List<Integer> res=new ArrayList<>();
if(root==null) return res;
List<TreeNode> row1=new ArrayList<>();
List<TreeNode> row2=new ArrayList<>();
List<TreeNode> tmp=new ArrayList<>();
row1.add(root);
res.add(root.val);
while(row1.size()>0) {
for(int i=0;i<row1.size();i++) {
if(row1.get(i).left!=null)
row2.add(row1.get(i).left);
if(row1.get(i).right!=null)
row2.add(row1.get(i).right);
}
if(row2.size()>0) {
res.add(row2.get(row2.size()-1).val);
}
tmp=row1;
row1=row2;
row2=tmp;
row2.clear();
}
return res;
}
}
运行结果: