Search in Rotated Sorted Array

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Thomson Reuters interview context: Search in Rotated Sorted Array is a Medium Binary Search problem — Binary search on index or on the answer (binary search on value).

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Pattern: Binary Search

Read from stdin, write to stdout. Classic interview problem #33.

Problem

Search in Rotated Sorted Array — Thomson Reuters interview prep · Binary Search

Classic interview problem #33.

Input (stdin)

Line 1: rotated array\nLine 2: target

Output (stdout)

Index or -1

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

Examples

Sample

Input

4 5 6 7 0 1 2
0

Output

Hints

Input format: Line 1: rotated array\nLine 2: target
DSA Interview 150 — Binary Search
Problem #33
Frequently asked at Thomson Reuters
Binary Search

Your 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()
    {
        // Read from stdin (see problem statement for format)
        // Line 1: rotated array\nLine 2: target

}
}

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

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 lo = 0, hi = nums.Length - 1, ans = -1;
while (lo <= hi) {
    int mid = lo + (hi - lo) / 2;
    if (nums[mid] == target) { ans = mid; break; }
    if (nums[lo] <= nums[mid]) {
        if (nums[lo] <= target && target < nums[mid]) hi = mid - 1; else lo = mid + 1;
    } else {
        if (nums[mid] < target && target <= nums[hi]) lo = mid + 1; else hi = mid - 1;
    }
}
Wi(ans);
    }
}

Try solving on your own first, then reveal the official answer.

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