Added bit manipulation algorithms.

bit_manipulation/hamming_distance.cpp

@@ -0,0 +1,40 @@
+/**
+ * @file
+ * @brief Returns the Hamming distance between two integers
+ *
+ * @details
+ * To find hamming distance between two integers, we take their xor, which will
+ * have a set bit iff those bits differ in the two numbers.
+ * Hence, we return the number of such set bits.
+ *
+ * @author [Ravishankar Joshi](https://github.com/ravibitsgoa)
+ */
+
+#include <iostream>
+using std::cout, std::endl;
+
+unsigned int bitCount(unsigned int value) {
+    unsigned int count = 0;
+    while (value) {       // until all bits are zero
+        if (value & 1) {  // check lower bit
+            count++;
+        }
+        value >>= 1;  // shift bits, removing lower bit
+    }
+    return count;
+}
+
+unsigned int hamming_distance(int a, int b) {
+    if (a < 0 || b < 0) {
+        throw "Both arguments must be >=0 for finding hamming distance.";
+    }
+    return bitCount(a ^ b);
+}
+
+int main() {
+    int a = 11;  // 1011 in binary
+    int b = 2;   // 0010 in binary
+
+    std::cout << "Hamming distance between " << a << " and " << b << " is "
+         << hamming_distance(a, b) << std::endl;
+}

bit_manipulation/power_of_2.cpp

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+/**
+ * @file
+ * @brief Finding if a number is a power of 2.
+ *
+ * @details
+ * To find if a number is a power of 2, we can check if bitwise AND of number
+ * and number - 1 is zero or not. Only for the numbers which are a power of 2,
+ * bitwise AND(x, x-1) is zero.
+ *
+ * @author [Ravishankar Joshi](https://github.com/ravibitsgoa)
+ */
+
+#include <iostream>
+#include <vector>
+using std::cout;
+using std::endl;
+using std::vector;
+
+bool ispower2(int x) { return x > 0 && (x & (x - 1)) == 0; }
+
+int main() {
+    vector<int> arr{1, 2, 3, 4, 8, 10};
+    for (int x : arr) {
+        cout << x << " is " << (ispower2(x) ? "" : "not ") << "a power of 2."
+             << endl;
+    }
+}

bit_manipulation/xor_swap.cpp

@@ -0,0 +1,19 @@
+/**
+ * @file
+ * @brief Swapping two integers using xor.
+ *
+ * @author [Ravishankar Joshi](https://github.com/ravibitsgoa)
+ */
+
+#include <iostream>
+using std::cout;
+using std::endl;
+
+int main() {
+    int a = 1, b = 2;
+    cout << "a = " << a << ", b = " << b << endl;
+    a ^= b;
+    b ^= a;
+    a ^= b;
+    cout << "a = " << a << ", b = " << b << endl;
+}