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algorithm notes: leetcode#606 construct string from binary tree

admin 11月 12, 2020 0

Problem

Solution

Analysis

Python implementation

class :
    def tree2str(self, t):
        """
        :type t: TreeNode
        :rtype: str
        """
        if t is None:
            return ''
        if t.left is None and t.right is None:
            return str(t.val)
        if t.right is None:
            return str(t.val) + '({})'.format(self.tree2str(t.left))
        return str(t.val) + '({})({})'.format(self.tree2str(t.left), self.tree2str(t.right))r

Java implementation

 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class  {
    public String tree2str(TreeNode t) {
        if(t == null)
            return ""; 
        if(t.left == null && t.right == null)
            return Integer.toString(t.val);
        if(t.right == null)
            return t.val + "(" + tree2str(t.left) + ")";
        return t.val + "(" + tree2str(t.left) + ")" + "(" + tree2str(t.right) + ")";
    }
}

Time complexity

O(n).

Space complexity

O(n).

Links

606. Construct String from Binary Tree
(中文版) 算法笔记: 力扣#606 根据二叉树创建字符串