From d2aca8d88f49a740b618a819634e829373bc6bf6 Mon Sep 17 00:00:00 2001
From: Matej Focko <me@mfocko.xyz>
Date: Tue, 12 Nov 2024 00:03:52 +0100
Subject: [PATCH] =?UTF-8?q?kt:=20add=20=C2=AB2601.=20Prime=20Subtraction?=
 =?UTF-8?q?=20Operation=C2=BB?=
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URL:	https://leetcode.com/problems/prime-subtraction-operation/
Signed-off-by: Matej Focko <me@mfocko.xyz>
---
 kt/prime-subtraction-operation.kt | 36 +++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)
 create mode 100644 kt/prime-subtraction-operation.kt

diff --git a/kt/prime-subtraction-operation.kt b/kt/prime-subtraction-operation.kt
new file mode 100644
index 0000000..66e674f
--- /dev/null
+++ b/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
+    }
+}