euler004.cpp

#include <iostream>
#include <math.h>

int main() {
    int w = 6;
    int l = pow(10, w - 1);
    int t = pow(10, w);
    int h = t - 1;

    for (long i = h; i > l; i--) {
        long b = i;
        long p = 0;
        for (int j = 1; b > 0; j++) {
            int e = pow(10, j);
            int r = b % e;
            p += pow(10, w - j) * (r / pow(10, j - 1));
            b -= r;
        }
        p = i * t + p;
        for (int j = h; j > l; j--) {
            if (p % j == 0 && p / j < t) {
                std::cout << p << " = " << j << " * " << p / j << std::endl;
                return 0;
            }
        }
    }
    return 0;
}

euler004.py

import sys

def euler004(w):
    l = 10 ** (w - 1)
    h = 10 ** w - 1
    t = 10 ** w
    for i in xrange(h, l, -1):
        s = str(i)
        p = int(s + s[::-1])
        for j in xrange(h, l, -1):
            if p % j == 0 and p / j < t:
                return p, j, p / j

print "%d = %d * %d" % euler004(int(sys.argv[1]))