FizzBuzz.java

import java.util.*;

class Solution {
  public List<String> fizzBuzz(int n) {
    List<String> list = new ArrayList<>();
    for (int i = 1; i <= n; i++) {
      String temp = "";
      if (i % 3 == 0) {
        temp += "Fizz";
      }
      if (i % 5 == 0) {
        temp += "Buzz";
      }
      if (temp.equals("")) {
        temp += i;
      }
      list.add(temp);
    }
    return list;
  }
}

// Generalized

class Solution {
  public List<String> fizzBuzz(int n) {

    // ans list
    List<String> ans = new ArrayList<String>();

    // Hash map to store all fizzbuzz mappings.
    HashMap<Integer, String> fizzBizzDict =
        new HashMap<Integer, String>() {
          {
            put(3, "Fizz");
            put(5, "Buzz");
          }
        };

    for (int num = 1; num <= n; num++) {

      String numAnsStr = "";

      for (Integer key : fizzBizzDict.keySet()) {

        // If the num is divisible by key,
        // then add the corresponding string mapping to current numAnsStr
        if (num % key == 0) {
          numAnsStr += fizzBizzDict.get(key);
        }
      }

      if (numAnsStr.equals("")) {
        // Not divisible by 3 or 5, add the number
        numAnsStr += Integer.toString(num);
      }

      // Append the current answer str to the ans list
      ans.add(numAnsStr);
    }

    return ans;
  }
}