two-sum.go

// Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target.
//
// You may assume that each input would have exactly one solution, and you may not use the same element twice.
//
// You can return the answer in any order.
//
//  
// Example 1:
//
//
// Input: nums = [2,7,11,15], target = 9
// Output: [0,1]
// Output: Because nums[0] + nums[1] == 9, we return [0, 1].
//
//
// Example 2:
//
//
// Input: nums = [3,2,4], target = 6
// Output: [1,2]
//
//
// Example 3:
//
//
// Input: nums = [3,3], target = 6
// Output: [0,1]
//
//
//  
// Constraints:
//
//
// 	2 <= nums.length <= 103
// 	-109 <= nums[i] <= 109
// 	-109 <= target <= 109
// 	Only one valid answer exists.
//
//


func twoSum(nums []int, target int) []int {
    hashTable := make(map[int]int)
	for i := 0; i < len(nums); i++ {
		diff := target - nums[i]
		if v, ok := hashTable[diff]; ok {
			return []int{v,i}
		}
		hashTable[nums[i]] = i
	}
	return nil
}