Given an array of integers, return indices of the two numbers such that they add up to a specific target. You may assume that each input would have exactly one solution, and you may not use the same element twice. Example: ~~~ Given nums = [2, 7, 11, 15], target = 9, Because nums[0] + nums[1] = 2 + 7 = 9, return [0, 1]. ~~~ ~~~ public class Solution { public int[] twoSum(int[] numbers, int target) { HashMap<Integer, Integer> map = new HashMap<Integer, Integer>(); int[] result = new int[2]; for (int i = 0; i < numbers.length; i++) { if (map.containsKey(numbers[i])) { int index = map.get(numbers[i]); result[0] = index ; result[1] = i; break; } else { map.put(target - numbers[i], i); } } return result; } } ~~~