Step through the algorithm visually — use Play or the step buttons (inspired by AlgoMaster / visualgo).
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.
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).
4 2 7 11 15 9
0 1
| Test | Status | Details |
|---|
Ready — edit the code above and click Run or Submit.
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);
}
}Try solving on your own first, then reveal the official answer.