feat: add Find non repeating number implementation (#2061)

* add find_single_number

* add fix issues

* remove .vscode

* add .vscode

* Update .vscode/settings.json

Co-authored-by: David Leal <halfpacho@gmail.com>

* chore(fix): minor issues

Co-authored-by: David Leal <halfpacho@gmail.com>

bit_manipulation/find_non_repeating_number.cpp

@@ -0,0 +1,88 @@
+/**
+ * @file
+ * @brief Implementation to find the non repeating integer
+ * in an array of repeating integers. [Single
+ * Number](https://leetcode.com/problems/single-number/)
+ *
+ * @details
+ * Given an array of integers in which all of the numbers occur exactly
+ * twice except one integer which occurs only once. Find the non-repeating
+ * integer.
+ *
+ * Worst Case Time Complexity: O(n)
+ * Space complexity: O(1)
+
+ * @author [Ravidev Pandey](https://github.com/literalEval)
+ */
+
+#include <cassert>   /// for assert
+#include <iostream>  /// for IO operations
+#include <vector>    /// storing the numbers
+
+/**
+ * @namespace bit_manipulation
+ * @brief Bit manipulation algorithms
+ */
+namespace bit_manipulation {
+/**
+ * @namespace find_non_repeating_integer
+ * @brief Functions to find the non repeating integer
+ * in an array of repeating integers. [Single
+ * Number](https://leetcode.com/problems/single-number/)
+ */
+namespace find_non_repeating_integer {
+/**
+ * @brief The main function implements find single number
+ * @param nums vector of integers
+ * @returns returns the integer that occurs only once
+ */
+int64_t find_non_repeating_integer(const std::vector<int>& nums) {
+    // The idea is based on the property of XOR.
+    // We know that 'a' XOR 'a' is '0' and '0' XOR 'b'
+    // is b.
+    // Using this, if we XOR all the elements of the array,
+    // the repeating elements will give '0' and this '0'
+    // with the single number will give the number itself.
+
+    int _xor = 0;
+
+    for (const int& num: nums) {
+        _xor ^= num;
+    }
+
+    return _xor;
+}
+}  // namespace find_non_repeating_integer
+}  // namespace bit_manipulation
+
+/**
+ * @brief Self-test implementations
+ * @returns void
+ */
+static void test() {
+    // n = 10,2 return 14
+
+    std::vector<int> nums_one{1, 1, 2, 2, 4, 5, 5};
+    std::vector<int> nums_two{203, 3434, 4545, 3434, 4545};
+    std::vector<int> nums_three{90, 1, 3, 90, 3};
+
+    assert(bit_manipulation::find_non_repeating_integer::
+               find_non_repeating_integer(nums_one) ==
+           4);  // 4 is non repeating
+    assert(bit_manipulation::find_non_repeating_integer::
+               find_non_repeating_integer(nums_two) ==
+           203);  // 203 is non repeating
+    assert(bit_manipulation::find_non_repeating_integer::
+               find_non_repeating_integer(nums_three) ==
+           1);  // 1 is non repeating
+
+    std::cout << "All test cases successfully passed!" << std::endl;
+}
+/**
+ * @brief Main function
+ * @returns 0 on exit
+ */
+int main() {
+    test();  // run self-test implementations
+    return 0;
+}