/*
Alexander DeTrano
2/1/2010
Project Euler - Problem 4

A palindromic number reads the same both ways. The largest palindrome made from the product of two 2-digit numbers is 9009 = 91  99.

Find the largest palindrome made from the product of two 3-digit numbers.
*/
#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int palindromecheck(int n);

int main(){
    vector<int> myArray;
    int num=0; int count=0;
    for(int i=1;i<=999;i++){
        for(int j=1;j<=999;j++){
            num=i*j;
        if(palindromecheck(num)==1){
            myArray.push_back(count); //expand size of array by 1
            myArray[count]=num;
            count+=1;
        }

        }
    }
cout<<myArray.size(); //#of elements before removing duplicats
sort(myArray.begin(),myArray.end()); //sort vector from small to large
myArray.erase(unique(myArray.begin(),myArray.end()),myArray.end()); //erase duplicates
cout<<myArray.size()<<endl; //print new size of array
cout<<"Max Palindrome is: "<<*(max_element( myArray.begin(), myArray.end() ) ); //find max element in array

return 0;
}


int palindromecheck(int n)
{
    int r,sum=0,temp,flag;
    temp=n;
    while(n){
        r=n%10;
        n=n/10;
        sum=sum*10+r;
    }

    if(temp==sum)
    flag=1;
    else
    flag=0;
    return flag;
}

Project Euler Problem 4

C++