Return two unique indices (one based) such that the values at those indices sums to the given target.

GoodPair.kt

/*
Given an array of integers nums and an integer target, 
return indices of the two numbers such that they add up to target.
Example:
Input: nums = [2,7,11,15], target = 9
Output: [0,1]
Explanation: Because nums[0] + nums[1] == 9, we return [0, 1].
* */
fun twoSum(nums: IntArray, target: Int): IntArray {
    val map: MutableMap<Int, Int> = mutableMapOf()
    for (i: Int in nums.indices) {
        if (map.containsKey(target - nums[i])) {
            return intArrayOf(map.get(target - nums[i])!!, i)
        } else {
            map.put(nums[i], i)
        }
    }
    return intArrayOf(0, 0)
}