Add longest increasing subsequence solution

Author: hyunjung-choi

longest-increasing-subsequence/hyunjung-choi.kt

@@ -0,0 +1,33 @@
+class Solution {
+    fun lengthOfLIS(nums: IntArray): Int {
+        val tails = mutableListOf<Int>()
+
+        for (num in nums) {
+            val pos = binarySearchLeftmost(tails, num)
+
+            if (pos == tails.size) {
+                tails.add(num)
+            } else {
+                tails[pos] = num
+            }
+        }
+
+        return tails.size
+    }
+
+    fun binarySearchLeftmost(list: List<Int>, target: Int): Int {
+        var left = 0
+        var right = list.size
+
+        while (left < right) {
+            val mid = left + (right - left) / 2
+            if (list[mid] < target) {
+                left = mid + 1
+            } else {
+                right = mid
+            }
+        }
+
+        return left
+    }
+}