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  3. Project Euler #4: Largest palindrome product
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Project Euler #4: Largest palindrome product

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  • ishwardharme320
     + 0 comments
    public static void main(String[] args) {

        List<Integer> list=new ArrayList<>();
        String x;
        StringBuilder sb;
        int ori;
        for(int i=999;i>=100;i--){
            for(int j=999;j>=100;j--){
                ori=i*j;
                x=String.valueOf(ori);
                sb=new StringBuilder(x);
                sb=sb.reverse();
                if(x.equals(sb.toString())){
                    list.add(ori);
                }
            }
        }
        Collections.sort(list,Collections.reverseOrder());


    Scanner in = new Scanner(System.in);
    int t = in.nextInt();
    for(int a0 = 0; a0 < t; a0++){
        int n = in.nextInt();
        for(int i=0;i<list.size();i++){
            if(list.get(i)<n){
                System.out.println(list.get(i));
                break;
            }
        }
    }

    }

  • dbiswas14
     + 0 comments

    public class Solution {

    public static void main(String[] args) {

    int l = 0;
    int f1 = 100;
    int limit = 999;
    int f2 =0;
    int smallest = 0;
    int[] arr;

    Scanner in = new Scanner(System.in);
    l = in.nextInt();
    arr = new int[l];

    for (int i = 0; i < l; i++) {

    // Pattern pttr = Pattern.compile("\d\d\d\d\d\d"); // Matcher m = pttr.matcher(String.valueOf()); // if (!m.matches()) { // // continue; // // } else { // // smallest = l; // //System.out.println(i); // //System.out.println(temp/i); // // // }

            arr[i]=in.nextInt();

    }

    for (int k = 0; k < 2; k++) {

        l=arr[k];

        while(true) {

            if(checkPalindrome(l)) {

                for(int i = f1 ; i<limit ; i++) {

                    if(l%i == 0) {



                        int temp = l;



                        Pattern pttr = Pattern.compile("\\d\\d\\d");
                        Matcher m = pttr.matcher(String.valueOf(temp/i));
                        if (!m.matches()) {

                            continue;

                        } else {

                            smallest = l;
                            //System.out.println(i);
                            //System.out.println(temp/i);


                        }


                        break;

                    }

                }

            }

            l=l-1;



            if (l<100000) {

                break;


            }

            if (smallest!=0) {

                break;

            }

        }

        System.out.println(smallest);
        smallest = 0;



    }





}



public static boolean checkPalindrome(int n) {

    String s = String.valueOf(n);

    if(s.charAt(0) == s.charAt(s.length()-1)) {

        int r = 0;
        int sum = 0;
        int temp = n;

        while (n>0) {

            r=n%10;  //getting remainder
            sum=(sum*10)+r;
            n=n/10;
        }

        if (temp == sum) {

            return true;
        }


    }

    return false;



}

    }

  • khanhduylenguye1
     + 0 comments
    //My code by C++,solving by the solution divide and conquer
#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


bool palindrome(long long n) {
    long long first_num = n;
    long long reverse = 0;

    while (n > 0) {
        long long num = n % 10;
        reverse = reverse * 10 + num;
        n /= 10;
    }

    return (first_num == reverse);
}
bool checker(int k){
    for(int i = 999; i >= 100; i--){
        if(k % i == 0 && k/i >= 100 && k/i <= 999){
            return true;
        }
    }
    return false;
}
signed main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */
    long long t;
    cin>>t;
    while(t--){
       long long n;
       cin>>n;
       for(long long i = n - 1; i >= 101101; i--){
           if(palindrome(i) == true && checker(i) == true) {
                cout<<i<<endl;
                i = INT8_MIN; //get out the "for loop"  when find i 
            }  
       } 
    }
    return (0^0);
}

  • naveen_35
     + 0 comments
    import java.io.*;
import java.util.*;


public class Solution {
    public static void main(String[] args) throws IOException {
        Scanner s=new Scanner(System.in);
        int t=s.nextInt();
        while(t-->0)
        {
            int n=s.nextInt();
            System.out.println(lar_Pal_lessthan_n(n));
        }
        s.close();
    }
        public static int lar_Pal_lessthan_n(int n)
        {
                for(int i= n-1;i>=101101;i--)
                {
                    if(ispal(i) && t2_t3fact(i) )
                    {
                        return i;
                    }
                }
            return -1;
        }
        
        public static boolean ispal(int n)
        {
            int org=n;
            int r=0;
            while(n!=0)
            {
                 r=r*10+n%10;
                n/=10;   
            }
            return org==r;
        }
        public static boolean t2_t3fact(int n)
        {
           for(int i=999;i>=100;i--)
           {
               if(n%i==0 && n/i>=100 && n/i<=999)
               {
               return true;
               }
           }
              return false;      
            
        }
}

    Happy Learning!

  • darwhin88
     + 0 comments

    t = int(input().strip()) for a0 in range(t): n = int(input().strip()) palindrome = 0

    while palindrome==0:
    n -=1
    if str(n)==str(n)[::-1]:
        for j in range(100, 999):
            f = n/j
            if f%1 == 0 and f <= 999:
                f= int(f)
                palindrome=n
                break

print(palindrome)#, "\n factors:", j, "X", f)