two sum

1bool twosum(int A[], int N, int X) {
2  	sort(A, A+N);
3    int i = 0, j = N-1;
4    while (i < j) {
5        if (A[i] + A[j] == X) return true;
6        else if (A[i] + A[j] > X) j--;
7        else i++;
8    }
9    return false;
10}

1class Solution {
2    public int[] twoSum(int[] nums, int target) {
3      int[] arr = new int[2];
4        
5        HashSet<Integer> hs = new HashSet<>();
6        
7        for(int i=0; i<nums.length; i++){
8            if(hs.contains(target-nums[i])){
9                arr[1] = i;
10                break;
11            }
12            hs.add(nums[i]);
13        }
14        
15        for(int i=0; i<nums.length; i++){
16            if(nums[i] == target - nums[arr[1]] && arr[1] != i)
17                arr[0] = i;
18        }
19        return arr;
20    }
21}
22