Trello job application question

gistfile1.md

Find an 8 letter string of characters that contains only letters from acdegilmnoprstuw such that the hash(the_string) is 25180466553932 if hash is defined by the following pseudo-code:

Int64 hash (String s) {
  Int64 h = 7   
  String letters = "acdegilmnoprstuw"     
  for(Int32 i = 0; i < s.length; i++) {
      h = (h * 37 + letters.indexOf(s[i]))     
  }
  return h
} 

For example, if we were trying to find the 7 letter string where hash(the_string) was 680131659347, the answer would be "leepadg".)

gistfile2.java

package com.vijaysharma;

public class Solution {
	private static final String letters = "acdegilmnoprstuw";
	private static final long target = 25180466553932L;
	
	public static void main(String[] args) {
		divide_and_conquer();
	}
	
	public static void divide_and_conquer() { 
		char[] test = {'a','a','a','a','a','a','a','a'};
		int it = 1;
		do {
			String string = new String(test);
			long hash = hash(string);
			long diff = target - hash;
			System.out.println((it++) + ": " + string + " h:" + hash + " d:" + diff);
			if (diff == 0) {
				System.out.println("success!");
				break;
			}
			for (int index = 7; index >= 0; index--) {
				double max = Math.pow(37, index);
				if (diff >= max) {
					int mod = test.length - 1 - index;
					int letter = letters.indexOf(test[mod]) + 1;
					test[mod] = letters.charAt(letter);
					break;
				}
			}
		} while(true);
	}
	
	public static void bruteforce() {
		for(int a = 0; a < letters.length(); a++ ) {
			for(int b = 0; b < letters.length(); b++ ) {
				for(int c = 0; c < letters.length(); c++ ) {
					for(int d = 0; d < letters.length(); d++ ) {
						for(int e = 0; e < letters.length(); e++ ) {
							for(int f = 0; f < letters.length(); f++ ) {
								for(int g = 0; g < letters.length(); g++ ) {
									for(int h = 0; h < letters.length(); h++ ) {
										StringBuilder test = new StringBuilder();
										test.append(letters.charAt(a));
										test.append(letters.charAt(b));
										test.append(letters.charAt(c));
										test.append(letters.charAt(d));
										test.append(letters.charAt(e));
										test.append(letters.charAt(f));
										test.append(letters.charAt(g));
										test.append(letters.charAt(h));
										
										String string = test.toString();
										long hash = hash(string);
										
										if (hash == 25180466553932L) {
											System.out.println("Success: " + string);
											return;
										} else {
											System.out.println(string + " h: " + hash);
										}
									}
								}
							}
						}
					}
				}
			}
		}
	}
	
	private static long hash(String string) {
		long h = 7;
		
		for (int i = 0; i < string.length(); i++ ) {
			h = (h * 37 + letters.indexOf(string.charAt(i)));
		}
		
		return h;
	}
}