LeetCode - Binary Tree Level Order Traversal II
把上一个类似的题目中的list反转就可以了。
/** * Definition for binary tree * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode(int x) { val = x; } * } */ public class Solution { public List<List<Integer>> levelOrderBottom(TreeNode root) { List<List<Integer>> list = new ArrayList<>(); List<List<Integer>> trlist = new ArrayList<>(); bfs(0, root, list); for(int i=list.size()-1; i>=0; i--) { trlist.add(list.get(i)); } return trlist; } public void bfs(int pos, TreeNode root, List<List<Integer>> list) { if(root==null) return; if(list.size() > pos) { list.get(pos).add(root.val); } else { List<Integer> l = new ArrayList<>(); l.add(root.val); list.add(l); } bfs(pos+1, root.left, list); bfs(pos+1, root.right, list); } }
作者:Pickle
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致读者:坚持写博客不容易,写高质量博客更难,我也在不断的学习和进步,希望和所有同路人一道用技术来改变生活。觉得有点用就点个赞哈。
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