Java打印树的所有路径

Posted 2022-11-01 yayun0516

        public boolean hasPathSum(TreeNode root, int sum) 
            List<Integer> list = new ArrayList<>();
            dfs(root, list);
            List<String> strings = new ArrayList<>();
            helper(root, root.val + "", strings);
            System.out.println(strings.toString());
            return true;
        

        public void helper(TreeNode root, String path, List<String> result) 
            if (root == null) 
                return;
            

            if (root.left == null && root.right == null) 
                result.add(path);
                return;
            

            if (root.left != null) 
                helper(root.left, path + "->" + root.left.val, result);
            

            if (root.right != null) 
                helper(root.right, path + "->" + root.right.val, result);
            
        



输出list集合：
  List<List<Integer>> results = new ArrayList<>();
        public boolean hasPathSum(TreeNode root, int sum) 
            List<Integer> list = new ArrayList<>();
            dfs(root, list);
            System.out.println(results.toString());
            return true;
        
        


        private void dfs(TreeNode root, List<Integer> list) 
            if (root == null) 
                return;
            
            if (root.left == null && root.right == null) 
                results.add(list);
            
            list.add(root.val);
            if (root.left != null) 
                dfs(root.left, new ArrayList<>(list));
            
            if (root.right != null) 
                dfs(root.right, new ArrayList<>(list));