From fae26676326e3b05128553944e143684cd4d3083 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Andr=C3=A9=20Borba?= <andre.borbaaf2b@gmail.com>
Date: Sat, 19 Sep 2026 09:24:22 -0300
Subject: [PATCH] =?UTF-8?q?=F0=9F=9F=A2=20Port=20problem=20136=20(Single?=
 =?UTF-8?q?=20Number)=20from=20Swift=20to=20C++23?=
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Replaces swift/136.swift with solutions/0101-0200/0136-single-number/.
XORs through an unsigned accumulator to avoid signed-bitwise UB
concerns on the int inputs.
---
 .../0101-0200/0136-single-number/README.md    | 12 ++++++
 .../0101-0200/0136-single-number/solution.cpp | 13 +++++++
 .../0101-0200/0136-single-number/solution.hpp | 10 +++++
 .../0101-0200/0136-single-number/test.cpp     |  8 ++++
 swift/136.swift                               | 37 -------------------
 5 files changed, 43 insertions(+), 37 deletions(-)
 create mode 100644 solutions/0101-0200/0136-single-number/README.md
 create mode 100644 solutions/0101-0200/0136-single-number/solution.cpp
 create mode 100644 solutions/0101-0200/0136-single-number/solution.hpp
 create mode 100644 solutions/0101-0200/0136-single-number/test.cpp
 delete mode 100644 swift/136.swift

diff --git a/solutions/0101-0200/0136-single-number/README.md b/solutions/0101-0200/0136-single-number/README.md
new file mode 100644
index 0000000..e586543
--- /dev/null
+++ b/solutions/0101-0200/0136-single-number/README.md
@@ -0,0 +1,12 @@
+# 136. Single Number
+
+[LeetCode problem 136](https://leetcode.com/problems/single-number/)
+
+- **Difficulty**: Easy
+- **Tags**: array, bit-manipulation
+
+## Description
+
+Given a non-empty array of integers where every element appears twice except
+for one, find that single element. Must run in O(n) time using O(1) extra
+space.
diff --git a/solutions/0101-0200/0136-single-number/solution.cpp b/solutions/0101-0200/0136-single-number/solution.cpp
new file mode 100644
index 0000000..cee0174
--- /dev/null
+++ b/solutions/0101-0200/0136-single-number/solution.cpp
@@ -0,0 +1,13 @@
+#include "solution.hpp"
+
+namespace leetcode::p0136 {
+
+int solve(const std::vector<int>& nums) {
+    unsigned result = 0;
+    for (int num : nums) {
+        result ^= static_cast<unsigned>(num);
+    }
+    return static_cast<int>(result);
+}
+
+} // namespace leetcode::p0136
diff --git a/solutions/0101-0200/0136-single-number/solution.hpp b/solutions/0101-0200/0136-single-number/solution.hpp
new file mode 100644
index 0000000..0bb1b42
--- /dev/null
+++ b/solutions/0101-0200/0136-single-number/solution.hpp
@@ -0,0 +1,10 @@
+#pragma once
+
+#include <vector>
+
+namespace leetcode::p0136 {
+
+// optimized: O(n) time, O(1) space — XOR cancels out every paired value.
+int solve(const std::vector<int>& nums);
+
+} // namespace leetcode::p0136
diff --git a/solutions/0101-0200/0136-single-number/test.cpp b/solutions/0101-0200/0136-single-number/test.cpp
new file mode 100644
index 0000000..14475fd
--- /dev/null
+++ b/solutions/0101-0200/0136-single-number/test.cpp
@@ -0,0 +1,8 @@
+#include <catch2/catch_test_macros.hpp>
+
+#include "solution.hpp"
+
+TEST_CASE("Problem 136", "[p0136]") {
+    CHECK(leetcode::p0136::solve({2, 2, 1}) == 1);
+    CHECK(leetcode::p0136::solve({4, 1, 2, 1, 2}) == 4);
+}
diff --git a/swift/136.swift b/swift/136.swift
deleted file mode 100644
index 5eee177..0000000
--- a/swift/136.swift
+++ /dev/null
@@ -1,37 +0,0 @@
-func singleNumber(_ nums: [Int]) -> Int {
-    var number = 0
-
-    for num in nums {
-        number ^= num
-    }
-
-    return number
-}
-
-func assertTrueInt(_ expectedValues: [Int], _ actualValues: [Int]) {
-    for i in 0..<expectedValues.count {
-        let expected = expectedValues[i]
-        let actual = actualValues[i]
-
-        if expected == actual {
-            print("Test case \(i) passed")
-        } else {
-            print("Test case \(i) failed")
-        }
-    }
-}
-
-var tests =
-    [
-        [2, 2, 1],
-        [4, 1, 2, 1, 2],
-    ]
-
-let expectedValues = [1, 4]
-var actualValues = [Int]()
-
-for i in 0..<tests.count {
-    actualValues.append(singleNumber(tests[i]))
-}
-
-assertTrueInt(expectedValues, actualValues)
\ No newline at end of file