From fa54cd1335fc3bd2f488b1c3cc97bdb493807717 Mon Sep 17 00:00:00 2001
From: Matej Focko <mfocko@redhat.com>
Date: Tue, 16 Aug 2022 11:10:52 +0200
Subject: [PATCH] =?UTF-8?q?problems:=20add=20=E2=80=9E387.=20First=20Uniqu?=
 =?UTF-8?q?e=20Character=20in=20a=20String=E2=80=9C?=
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Signed-off-by: Matej Focko <mfocko@redhat.com>
---
 .../first-unique-character-in-a-string.kt     | 26 +++++++++++++++++++
 1 file changed, 26 insertions(+)
 create mode 100644 problems/first-unique-character-in-a-string.kt

diff --git a/problems/first-unique-character-in-a-string.kt b/problems/first-unique-character-in-a-string.kt
new file mode 100644
index 0000000..49a44bd
--- /dev/null
+++ b/problems/first-unique-character-in-a-string.kt
@@ -0,0 +1,26 @@
+class Solution {
+    private data class Accumulator(val firstIndex: Int, var count: Int = 0) {
+        fun add() {
+            count++
+        }
+    }
+
+    fun firstUniqChar(s: String): Int = s
+        .foldIndexed(mutableMapOf<Char, Accumulator>()) { i, acc, c ->
+            acc.getOrPut(c) { Accumulator(i) }.add()
+            acc
+        }
+        .filterValues { it.count == 1 }
+        .minByOrNull { (_, acc) -> acc.firstIndex }
+        ?.value
+        ?.firstIndex
+        ?: -1
+}
+
+fun main() {
+    val s = Solution()
+
+    check(s.firstUniqChar("leetcode") == 0)
+    check(s.firstUniqChar("loveleetcode") == 2)
+    check(s.firstUniqChar("aabb") == -1)
+}