Question

How to find a list of numbers up to a limit that is a palindrome in base 10 and base 2 in Go

Answer 1

package main

import (
    "fmt"
    "strings"
)

// Function to check if a number is a palindrome in a given base
func isPalindrome(num, base int) bool {
    if base < 2 {
        return false // Invalid base
    }

    var strnumReversed strings.Builder
    temp := num

    // Convert number to string in given base
    for {
        digit := temp % base
        if digit < 10 {
            strnumReversed.WriteByte(byte('0' + digit))
        } else {
            strnumReversed.WriteByte(byte('A' + (digit - 10)))
        }
        temp /= base
        if temp == 0 {
            break
        }
    }

    // Check palindrome
    str := strnumReversed.String()

    return str == reverseString(str)
}

// Helper function to reverse a string
func reverseString(s string) string {
    runes := []rune(s)
    for i, j := 0, len(runes) - 1; i < j; i, j = i + 1, j - 1 {
        runes[i], runes[j] = runes[j], runes[i]
    }
    return string(runes)
}

func main() {
    limit := 1000

    fmt.Println("Numbers that are palindromes in both base 10 and base 2:")
    for i := 1; i <= limit; i++ {
        if isPalindrome(i, 10) && isPalindrome(i, 2) {
            fmt.Printf("%d (binary: ", i)

            // Print binary representation
            var binary strings.Builder
            temp := i
            for {
                if temp % 2 == 1 {
                    binary.WriteByte('1')
                } else {
                    binary.WriteByte('0')
                }
                temp /= 2
                if temp == 0 {
                    break
                }
            }

            binaryStr := reverseString(binary.String())
            fmt.Printf("%s)\n", binaryStr)
        }
    }
}



/*
run:

Numbers that are palindromes in both base 10 and base 2:
1 (binary: 1)
3 (binary: 11)
5 (binary: 101)
7 (binary: 111)
9 (binary: 1001)
33 (binary: 100001)
99 (binary: 1100011)
313 (binary: 100111001)
585 (binary: 1001001001)
717 (binary: 1011001101)

*/

 

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