Add Pair Sum Unsorted

Author: marttp

kotlin/Hash Maps and Sets/PairSumUnSortedTwoPass.kt

@@ -0,0 +1,16 @@
+fun pairSumUnsortedTwoPass(nums: List<Int>, target: Int): List<Int> {
+    val numMap = mutableMapOf<Int, Int>()
+    // First pass: Populate the hash map with each number and its 
+    // index.
+    for ((i, num) in nums.withIndex()) {
+        numMap[num] = i
+    }
+    // Second pass: Check for each number's complement in the hash map.
+    for ((i, num) in nums.withIndex()) {
+        val complement = target - num
+        if (complement in numMap && numMap[complement] != i) {
+            return listOf(i, numMap[complement]!!)
+        }
+    }
+    return emptyList()
+}

kotlin/Hash Maps and Sets/PairSumUnsorted.kt

@@ -0,0 +1,10 @@
+fun pairSumUnsorted(nums: List<Int>, target: Int): List<Int> {
+    val hashmap = mutableMapOf<Int, Int>()
+    for ((i, x) in nums.withIndex()) {
+        if (target - x in hashmap) {
+            return listOf(hashmap[target - x]!!, i)
+        }
+        hashmap[x] = i
+    }
+    return emptyList()
+}