From 66888a41091cb053cf772c9d70d66b3e47aa149e Mon Sep 17 00:00:00 2001
From: Matej Focko <mfocko@redhat.com>
Date: Sat, 13 Aug 2022 22:50:35 +0200
Subject: [PATCH] =?UTF-8?q?problems:=20add=20=E2=80=9E30.=20Substring=20wi?=
 =?UTF-8?q?th=20Concatenation=20of=20All=20Words=E2=80=9C?=
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Signed-off-by: Matej Focko <mfocko@redhat.com>
---
 ...bstring-with-concatenation-of-all-words.kt | 29 +++++++++++++++++++
 1 file changed, 29 insertions(+)
 create mode 100644 problems/substring-with-concatenation-of-all-words.kt

diff --git a/problems/substring-with-concatenation-of-all-words.kt b/problems/substring-with-concatenation-of-all-words.kt
new file mode 100644
index 0000000..640e1f0
--- /dev/null
+++ b/problems/substring-with-concatenation-of-all-words.kt
@@ -0,0 +1,29 @@
+class Solution {
+    private fun buildTable(words: Sequence<String>): Map<String, Int> {
+        val table = mutableMapOf<String, Int>()
+
+        words.forEach {
+            table.put(it, 1 + table.getOrElse(it) { 0 })
+        }
+
+        return table
+    }
+    private fun buildTable(s: String, length: Int): Map<String, Int> =
+        buildTable(s.chunked(length).asSequence())
+
+    fun findSubstring(s: String, words: Array<String>): List<Int> {
+        val expectedFrequencies = buildTable(words.asSequence())
+        val wordLen = words.first().length
+        val windowSize = wordLen * words.size
+
+        return s
+            .windowed(windowSize)
+            .zip(s.indices)
+            .filter { (window, _) ->
+                val frequencies = buildTable(window, wordLen)
+                frequencies == expectedFrequencies
+            }
+            .map { (_, idx) -> idx }
+            .toList()
+    }
+}