Two Sum

func twoSum(nums []int, target int) []int {
	seen := make(map[int]int)

	for i, x := range nums {
		if j, ok := seen[target - x]; ok {
			return []int{i, j}
		}
		seen[x] = i
	}

	return []int{}
}

class Solution {
    public int[] twoSum(int[] nums, int target) {
        int len = nums.length;
        HashMap<Integer, Integer> mem = new HashMap<Integer, Integer>();
        int[] result = new int[2];

        //First element handling: You are initializing the mem map with the
        // first element of the array before the loop starts. 
        //This can cause issues if the first element itself is 
        //part of the solution.
        mem.put(nums[0], 0);
        for(int i=0; i < nums.length; i++){
        // Index out of bounds exception: In the for loop, 
        // you access nums[j] where j = i + 1. 
        // When i is the last index (nums.length - 1), 
        // j will be nums.length, causing an IndexOutOfBoundsException.
    
    
            int j = i+1;
            if(mem.containsKey(target-nums[j])) {
                // Return order: The problem typically asks for 
                // indices in increasing order, 
                // but this solution may not guarantee this.
                result[0] = j;
                result[1] = mem.get(target-nums[j]);
                break;
            }else{
                mem.put(nums[j], j);
            }
        }
        
        return result;

    }
}

class Solution {
    public int[] twoSum(int[] nums, int target) {
        HashMap<Integer, Integer> mem = new HashMap<>();

        for(int i = 0; i < nums.length; i++){
            int secondNumber = target - nums[i];
            if(mem.containsKey(secondNumber)){
                return new int[]{mem.get(secondNumber), i};
            }
            mem.put(nums[i], i);
        }
        return new int[]{-1,-1};
    }
}