kt: add «2601. Prime Subtraction Operation»

URL:	https://leetcode.com/problems/prime-subtraction-operation/
Signed-off-by: Matej Focko <me@mfocko.xyz>

kt/prime-subtraction-operation.kt

@@ -0,0 +1,36 @@
+class Solution {
+    private fun getPrimes(nums: IntArray): BooleanArray {
+        val primes = BooleanArray(1 + nums.max()) { true }
+        primes[1] = false
+
+        (2..sqrt(primes.size.toDouble()).toInt())
+            .asSequence()
+            .filter { primes[it] }
+            .forEach { i ->
+                (i * i..<primes.size step i).forEach { j ->
+                    primes[j] = false
+                }
+            }
+
+        return primes
+    }
+
+    fun primeSubOperation(nums: IntArray): Boolean {
+        val primes = getPrimes(nums)
+
+        var (current, i) = 1 to 0
+        while (i < nums.size) {
+            val difference = nums[i] - current
+            if (difference < 0) {
+                return false
+            }
+
+            if (primes[difference] || difference == 0) {
+                i += 1
+            }
+            current += 1
+        }
+
+        return true
+    }
+}