From 8171cd6289900c0d7fa1bfa9b82fb2bde1426c30 Mon Sep 17 00:00:00 2001
From: Matej Focko <mfocko@redhat.com>
Date: Sun, 7 Jan 2024 13:49:00 +0100
Subject: [PATCH] =?UTF-8?q?cs:=20add=20=E2=80=9C1657.=20Determine=20if=20T?=
 =?UTF-8?q?wo=20Strings=20Are=20Close=E2=80=9D?=
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Signed-off-by: Matej Focko <mfocko@redhat.com>
---
 cs/determine-if-two-strings-are-close.cs | 33 ++++++++++++++++++++++++
 1 file changed, 33 insertions(+)
 create mode 100644 cs/determine-if-two-strings-are-close.cs

diff --git a/cs/determine-if-two-strings-are-close.cs b/cs/determine-if-two-strings-are-close.cs
new file mode 100644
index 0000000..e77f723
--- /dev/null
+++ b/cs/determine-if-two-strings-are-close.cs
@@ -0,0 +1,33 @@
+public class Solution {
+    private static List<int> Freqs(string word) {
+        var f = new List<int>(Enumerable.Repeat(0, 26));
+
+        foreach (var c in word) {
+            ++f[c - 'a'];
+        }
+
+        return f;
+    }
+
+    private static int Mask(List<int> f) {
+        var m = 0;
+
+        foreach (var c in f) {
+            m = (m << 1) | (c > 0 ? 1 : 0);
+        }
+
+        return m;
+    }
+
+    public bool CloseStrings(string word1, string word2) {
+        var f1 = Freqs(word1);
+        var m1 = Mask(f1);
+        f1.Sort();
+
+        var f2 = Freqs(word2);
+        var m2 = Mask(f2);
+        f2.Sort();
+
+        return m1 == m2 && f1.SequenceEqual(f2);
+    }
+}