Solution to Two Sum problem using HashMap

TwoSum.java

class Solution {
    public int[] twoSum(int[] nums, int target) {
        // Hashmap to store remainder as key and current index as value
        Map<Integer, Integer> map = new HashMap<>();
        for(int i = 0; i < nums.length; i++) {
            if(map.containsKey(nums[i])) {
                // checks if map already contains value
                return new int[]{i, map.get(nums[i])};
            } else {
                // putting remainder and current index in map
                map.put(target - nums[i], i);
            }
        }
        return null;
    }
}