Two Sum II - Input Array Is Sorted

Medium 30 pts New · no attempts yet csharp

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Two Sum II - Input Array Is Sorted — Thomson Reuters interview prep · Two Pointers

Classic interview problem #167.

Input (stdin)

Line 1: sorted integers\nLine 2: target

Output (stdout)

Two indices (1-based), space-separated

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

Examples

Sample

Input

2 7 11 15
9

Output

1 2

Static hints

Input format: Line 1: sorted integers\nLine 2: target
DSA Interview 150 — Two Pointers
Problem #167
Frequently asked at Thomson Reuters
Two Pointers

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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: sorted integers\nLine 2: target

}
}

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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 nums = Ria();
int target = int.Parse(Console.ReadLine());
int l = 0, r = nums.Length - 1;
while (l < r) {
    int sum = nums[l] + nums[r];
    if (sum == target) break;
    if (sum < target) l++; else r--;
}
W(l + 1, r + 1);
    }
}

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Explanation

Step 1 / 1

Thomson Reuters interview context: Two Sum II - Input Array Is Sorted is a Medium Two Pointers problem — Shrink the search space from both ends; works on sorted arrays and palindromes.

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

Pattern: Two Pointers

Read from stdin, write to stdout. Classic interview problem #167.

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