Boundary of Binary Tree

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Problem Description

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Solutions

Solution 1: C# (Best: 244 ms)

Metric	Value
Runtime	244 ms
Memory	32.7 MB
Date	2020-01-13

Solution

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     public int val;
 *     public TreeNode left;
 *     public TreeNode right;
 *     public TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public IList<int> BoundaryOfBinaryTree(TreeNode root) {
        List<int> result = new List<int>();
    if(root == null) return result;
    result.Add(root.val);
    LeftBoundary(result, root.left);
    Leaves(result, root.left);
    Leaves(result, root.right);
    RightBoundary(result, root.right);
    return result;
}

void LeftBoundary(List<int> result, TreeNode root)
{
    if(root == null || (root.left == null && root.right == null)) return;
    result.Add(root.val);
    if(root.left == null) LeftBoundary(result, root.right);
    LeftBoundary(result, root.left);
}

void Leaves(List<int> result, TreeNode root)
{
    if (root == null ) return;
    if (root.left == null && root.right == null)
    {
        result.Add(root.val); return;
    }
    Leaves(result, root.left);
    Leaves(result, root.right);
}

void RightBoundary(List<int> result, TreeNode root)
{
    if (root == null || (root.left == null && root.right == null)) return;
    if (root.right == null) RightBoundary(result, root.left);
    RightBoundary(result, root.right);
    result.Add(root.val);
}

}

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Complexity Analysis

Approach	Time	Space
Solution	To be analyzed	To be analyzed