【leetcode】257（Easy）Binary Tree Paths

思路

DFS

提交代码

class Solution { public List<String> binaryTreePaths(TreeNode root) { List<String> res=new ArrayList<>(); if(root==null) return res; if(root.left==null&&root.right==null) { res.add(Integer.toString(root.val)); return res; } StringBuilder curPath=new StringBuilder(); curPath.append(Integer.toString(root.val)); if(root.left!=null) addPath(root.left,curPath,res); if(root.right!=null) addPath(root.right,curPath,res); return res; } public void addPath(TreeNode root,StringBuilder path,List<String> res) { int len=path.length(); path.append("->"); path.append(Integer.toString(root.val)); if(root.left==null&&root.right==null) { res.add(path.toString()); }else { if(root.left!=null) addPath(root.left,path,res); if(root.right!=null) addPath(root.right,path,res); } path.delete(len, path.length()); } }

运行结果