Add Longest Chain Of Consecutive Numbers

Author: marttp

kotlin/Hash Maps and Sets/LongestChainOfConsecutiveNumbers.kt

@@ -0,0 +1,22 @@
+fun longestChainOfConsecutiveNumbers(nums: List<Int>): Int {
+    if (nums.isEmpty()) {
+        return 0
+    }
+    val numSet = nums.toSet()
+    var longestChain = 0
+    for (num in numSet) {
+        // If the current number is the smallest number in its chain, search for
+        // the length of its chain.
+        if (num - 1 !in numSet) {
+            var currentNum = num
+            var currentChain = 1
+            // Continue to find the next consecutive numbers in the chain.
+            while (currentNum + 1 in numSet) {
+                currentNum++
+                currentChain++
+            }
+            longestChain = maxOf(longestChain, currentChain)
+        }
+    }
+    return longestChain
+}

kotlin/Hash Maps and Sets/LongestChainOfConsecutiveNumbersBruteForce.kt

@@ -0,0 +1,18 @@
+fun longestChainOfConsecutiveNumbersBruteForce(nums: List<Int>): Int {
+    if (nums.isEmpty()) {
+        return 0
+    }
+    var longestChain = 0
+    // Look for chains of consecutive numbers that start from each number.
+    for (num in nums) {
+        var currentNum = num
+        var currentChain = 1
+        // Continue to find the next consecutive numbers in the chain.
+        while (currentNum + 1 in nums) {
+            currentNum++
+            currentChain++
+        }
+        longestChain = maxOf(longestChain, currentChain)
+    }
+    return longestChain
+}