Valid Palindrome

Easy 20 pts New · no attempts yet csharp

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Valid Palindrome — Wix interview prep · Two Pointers

Classic interview problem #125.

Input (stdin)

Line 1: string

Output (stdout)

true or false

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

Examples

Sample

Input

A man, a plan, a canal: Panama

Output

true

Static hints

Input format: Line 1: string
DSA Interview 150 — Two Pointers
Problem #125
Frequently asked at Wix
Two Pointers

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Stuck? Get a nudge — not the answer

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Your solution

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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()
    {
string s = Console.ReadLine();
int l = 0, r = s.Length - 1;
bool ok = true;
while (l < r) {
    while (l < r && !char.IsLetterOrDigit(s[l])) l++;
    while (l < r && !char.IsLetterOrDigit(s[r])) r--;
    if (char.ToLower(s[l]) != char.ToLower(s[r])) { ok = false; break; }
    l++; r--;
}
Wb(ok);
    }
}

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Explanation

Step 1 / 1

Wix interview context: Valid Palindrome is a Easy 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 #125.

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