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  3. Project Euler #36: Double-base palindromes
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Project Euler #36: Double-base palindromes

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26 Discussions

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  • hilalaksoy6107
     + 0 comments

    100% working C programming

    include

    include

    include

    include

    include

    include

    include

    include

    void to_base(int n, int k, char *result) {

    int index = 0;

while (n > 0) {
    int remainder = n % k;
    result[index++] = (remainder < 10) ? (remainder + '0') : (remainder - 10 + 'a');
    n /= k;
}
result[index] = '\0';

int len = strlen(result);
for (int i = 0; i < len/2; ++i) {
    char temp = result[i];
    result[i] = result[len - 1 - i];
    result[len - 1 - i] = temp;
}

    }

    int is_palindroms(const char *str) {

    int len = strlen(str);
for (int i = 0; i < len/2; ++i) {

    if (str[i] != str[len - 1 - i]) {
        return 0;
    }
}
return 1;

    }

    int main() {

    int n, k;
scanf("%d %d", &n, &k);

int sum = 0;
char base_k[64];

for (int i = 1; i <= n; ++i) {
    char decimal_str[64];
    sprintf(decimal_str, "%d", i);

    if (is_palindroms(decimal_str)) {
        to_base(i, k, base_k);

        if (is_palindroms(base_k)) {
            sum += i;
        }
    }
}
printf("%d\n", sum);
/* Enter your code here. Read input from STDIN. Print output to STDOUT */    
return 0;

    }

  • mln19
     + 0 comments

    Solution without modulo convertion | Java 100p

    import java.io.*;
import java.util.*;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int k = in.nextInt();
        System.out.println(getPalindromsSum(n, k));
    }
    
    private static  long getPalindromsSum(int n, int k) {
        int[] digits10 = new int[100];
        int[] digitsK = new int[100];
        long sum = 1;
        int size10 = 1;
        int sizeK = 1;
        digits10[0] = 1;
        digitsK[0] = 1;
        for (int i=2; i<n; ++i) {
            size10 = incrementDigits(digits10, 10, size10);
            sizeK = incrementDigits(digitsK, k, sizeK);
            if (isPalindrom(digits10, size10) && isPalindrom(digitsK, sizeK))
                sum += i;
        }
        return sum;
    }

    private static int incrementDigits(int[] digits, int k, int sizeDigits) {
        int p = 0;
        while (digits[p] == k-1) {
            digits[p] = 0;
            p++;
        }
        digits[p] = digits[p] + 1;
        return Math.max(p+1, sizeDigits);
    }
    
    private static boolean isPalindrom(int[] digits, int sizeDigits) {
        int max = sizeDigits/2;
        for (int i=0; i<max; ++i) {
            if (digits[i] != digits[sizeDigits-1-i]) {
                return false;
            }
        }
        return true;
    }
}

  • Venkateshgurram5
     + 0 comments

    100 points.

    def convert(n,b):
    if n==0:
        return 0
    res=''
    while n>0:
        n,r=divmod(n,b)
        res=str(r)+res
    return res    
n,k=map(int,input().strip().split())
s=0
for i in range(1,n):
    c=convert(i,k)
    if str(i)==str(i)[::-1] and c==c[::-1]:
        s+=i
print(s)

  • ketan_patel25
     + 0 comments

    JAva Code

    import java.io.*;
import java.util.*;

public class Solution {

    
    static String valid(int n, int k) {
        StringBuilder s = new StringBuilder();
        while (n > 0) {
            int r = n % k;
            n /= k;
            s.append(Integer.toString(r));
        }
        return s.reverse().toString();
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String[] input = scanner.nextLine().split(" ");
        int n = Integer.parseInt(input[0]);
        int k = Integer.parseInt(input[1]);
        int t = 0;

        for (int i = 1; i <= n; i++) {
            String strI = Integer.toString(i);
            if (strI.equals(new StringBuilder(strI).reverse().toString())) {
                String validStr = valid(i, k);
                if (validStr.equals(new StringBuilder(validStr).reverse().toString())) {
                    t += i;
                }
            }
        }

        System.out.println(t);
        scanner.close();
    }
}

  • umairg404
     + 0 comments

    here is my c# 100 ponits solution

    using System;

class Solution {
    static string Valid(int n, int k) {
        string s = "";
        while (n > 0) {
            int r = n % k;
            n /= k;
            s += r.ToString();
        }
        char[] charArray = s.ToCharArray();
        Array.Reverse(charArray);
        return new string(charArray);
    }

    static void Main(string[] args) {
        string[] input = Console.ReadLine().Split();
        int n = int.Parse(input[0]);
        int k = int.Parse(input[1]);
        int t = 0;

        for (int i = 1; i <= n; i++) {
            if (i.ToString() == new string(i.ToString().ToCharArray().Reverse().ToArray())) {
                if (Valid(i, k) == new string(Valid(i, k).ToCharArray().Reverse().ToArray())) {
                    t += i;
                }
            }
        }

        Console.WriteLine(t);
    }
}