Two Sum

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Two Sum — HCLTech interview prep · Arrays & Hashing

Classic interview problem #1.

Input (stdin)

Line 1: n\nLine 2: n integers\nLine 3: target

Output (stdout)

Two indices (0-based), space-separated

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

Examples

Sample

Input

4
2 7 11 15
9

Output

0 1

Static hints

Input format: Line 1: n\nLine 2: n integers\nLine 3: target
DSA Interview 150 — Arrays & Hashing
Problem #1
Frequently asked at HCLTech
Arrays & Hashing

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Stuck? Get a nudge — not the answer

Progressive help: Nudge → Guide → Approach. Full solution stays behind the Solution tab.

Your solution

Editor is open — no login wall to practice.

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: n\nLine 2: n integers\nLine 3: target

}
}

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()
    {
int n = int.Parse(Console.ReadLine());
var nums = Ria();
int target = int.Parse(Console.ReadLine());
var map = new Dictionary<int, int>();
int a = 0, b = 0;
for (int i = 0; i < nums.Length; i++) {
    int need = target - nums[i];
    if (map.TryGetValue(need, out int j)) { a = j; b = i; break; }
    map[nums[i]] = i;
}
W(a, b);
    }
}

Prefer Coach (Nudge → Guide → Approach) before revealing. No forced signup.

Explanation

Step 1 / 1

HCLTech interview context: Two Sum is a Easy Arrays & Hashing problem — Use a hash map to trade space for O(1) lookups — classic at onsite rounds.

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

Pattern: Arrays & Hashing

Read from stdin, write to stdout. Classic interview problem #1.

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