kingsubin

class Solution {
    public int[] twoSum(int[] nums, int target) {
        for (int i = 0; i < nums.length - 1; i++) {
            int answer = target - nums[i];
            for (int j = i + 1; j < nums.length; j++) {
                if (answer - nums[j] == 0) {
                    return new int[] {i, j};
                }
            }
        }
        return null;
    }
}

 

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class Solution {
    public int[] twoSum(int[] nums, int target) {
        HashMap<Integer, Integer> hashMap = new HashMap<>();
        for (int i = 0; i < nums.length; i++) {
            if (hashMap.containsKey(target - nums[i])) {
                return new int[] {i, hashMap.get(target - nums[i])};
            } else {
                hashMap.put(nums[i], i);
            }
        }
 
        return null;
    }
}