Best Time to Buy and Sell Stock

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American Express interview context: Best Time to Buy and Sell Stock is a Easy Sliding Window problem — Maintain a window [L, R] and update counts as you expand or contract.

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

Pattern: Sliding Window

Read from stdin, write to stdout. Classic interview problem #121.

Problem

Best Time to Buy and Sell Stock — American Express interview prep · Sliding Window

Classic interview problem #121.

Input (stdin)

Line 1: daily prices

Output (stdout)

Max profit

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

Examples

Sample

Input

7 1 5 3 6 4

Output

Hints

Input format: Line 1: daily prices
DSA Interview 150 — Sliding Window
Problem #121
Frequently asked at American Express
Sliding Window

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: daily prices

}
}

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 prices = Ria();
int min = int.MaxValue, best = 0;
foreach (var p in prices) { min = Math.Min(min, p); best = Math.Max(best, p - min); }
Wi(best);
    }
}

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

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