1 package com.sam.twisters.euler;
 2 /* Problem 5 : Euler 
 3  * 2520 is the smallest number that can be divided by each of the numbers from 1 to 10 without any remainder.
 4  * What is the smallest number that is evenly divisible (divisible without reminder) by all of the numbers from 1 to 20?
 5 */
 6 
 7 public class prog5 {
 8     /*Simple function to check if the divisor completely divides the divident*/
 9     public static boolean isDivisble(int divident, int divisor)    {
10         if(divident%divisor == 0){
11             return true;
12         }
13         else{
14             return false;
15         }
16     }
17 
18     public static void main(String[] args) 
19     {
20         long startTime = System.nanoTime();
21         boolean va = true;
22         
23         /* Start looping though all the numbers and see if we can find one divisible by all numbers 
24          * from 1 to 20.
25          */
26         int i = 1;
27         do{
28             va = true;    //Assume that i is a valid answer to the puzzle
29 //Optimization -->for(int d=1;d<=20;d++){ 
30 /*(1 char, start from 11 and not 1). 
31 This works since atleast one of the numbers from 11 to 20 has each of the numbers 1-10 as a factor,
32 so for example when we test if a number is divisble by 12 - we also indirectly test that the 
33 number is divisible by 2,3,4 and 6
34 */
35             for(int d=11;d<=20;d++){
36                 if (!isDivisble(i, d)){    //Yikes my assumption was wrong!
37                     va = false;
38 //Optimization -->break;        (6 char)
39                     break;
40                 }
41             }
42             i++;
43         }while(!va);
44         System.out.println(i);
45         long estimatedTime = System.nanoTime() - startTime;
46         System.out.println((float)estimatedTime/1000000000);
47     }
48 }