Construct Binary Tree from Preorder and Inorder Traversal

Medium 30 pts New · no attempts yet csharp

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Construct Binary Tree from Preorder and Inorder Traversal — Trimble interview prep · Trees

Classic interview problem #105.

Input (stdin)

Line 1: level-order (-1 = null)

Output (stdout)

Tree aggregate (Construct Binary Tree from Preorder and Inorder Traversal)

Your program must read from stdin and write the answer to stdout (no extra debug text).

Examples

Sample

Input

3 9 20 -1 -1 15 7

Output

Static hints

Input format: Line 1: level-order (-1 = null)
DSA Interview 150 — Trees
Problem #105
Frequently asked at Trimble
Trees

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Your solution

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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

class Program
{
    static int[] Ria(string line = null)
    {
        line ??= Console.ReadLine();
        if (string.IsNullOrWhiteSpace(line)) return Array.Empty<int>();
        return line.Trim().Split(new[] { ' ', ',', '\t' }, StringSplitOptions.RemoveEmptyEntries)
            .Select(int.Parse).ToArray();
    }
    static string[] Rsa()
    {
        int n = int.Parse(Console.ReadLine());
        var arr = new string[n];
        for (int i = 0; i < n; i++) arr[i] = Console.ReadLine();
        return arr;
    }
    static void W(params object[] parts) => Console.WriteLine(string.Join(" ", parts));
    static void Wb(bool v) => Console.WriteLine(v ? "true" : "false");
    static void Wi(int v) => Console.WriteLine(v);
    static void Ws(string v) => Console.WriteLine(v);

static void Main()
    {
        // Read from stdin (see problem statement for format)
        // Line 1: level-order (-1 = null)

}
}

Ready — edit the code above and click Run or Submit.

Official solution

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

class Program
{
    static int[] Ria(string line = null)
    {
        line ??= Console.ReadLine();
        if (string.IsNullOrWhiteSpace(line)) return Array.Empty<int>();
        return line.Trim().Split(new[] { ' ', ',', '\t' }, StringSplitOptions.RemoveEmptyEntries)
            .Select(int.Parse).ToArray();
    }
    static string[] Rsa()
    {
        int n = int.Parse(Console.ReadLine());
        var arr = new string[n];
        for (int i = 0; i < n; i++) arr[i] = Console.ReadLine();
        return arr;
    }
    static void W(params object[] parts) => Console.WriteLine(string.Join(" ", parts));
    static void Wb(bool v) => Console.WriteLine(v ? "true" : "false");
    static void Wi(int v) => Console.WriteLine(v);
    static void Ws(string v) => Console.WriteLine(v);

    static void Main()
    {
var vals = Ria();
Wi(vals.Where(x => x >= 0).Sum());
    }
}

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Explanation

Step 1 / 1

Trimble interview context: Construct Binary Tree from Preorder and Inorder Traversal is a Medium Trees problem — DFS (recursion/stack) or BFS (queue); clarify preorder/inorder/postorder.

Use the animation above to step through each move before writing code.

Pattern: Trees

Read from stdin, write to stdout. Classic interview problem #105.

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