snippets

public int[] twoSum(int[] nums, int target) {
    Map<Integer, Integer> seen = new HashMap<>();
    for (int i = 0; i < nums.length; i++) {
        int need = target - nums[i];
        if (seen.containsKey(need)) {
            return new int[]{seen.get(need), i};
        }
        seen.put(nums[i], i);
    }
    return new int[]{};
}