From edda74711df6bf26ae14cc5ef1065e2a112e33d0 Mon Sep 17 00:00:00 2001
From: Swastika Gupta <64654203+Swastyy@users.noreply.github.com>
Date: Sun, 27 Jun 2021 21:34:03 +0530
Subject: [PATCH] Create count_of_set_bits.cpp

---
 bit_manipulation/count_of_set_bits.cpp | 69 ++++++++++++++++++++++++++
 1 file changed, 69 insertions(+)
 create mode 100644 bit_manipulation/count_of_set_bits.cpp

diff --git a/bit_manipulation/count_of_set_bits.cpp b/bit_manipulation/count_of_set_bits.cpp
new file mode 100644
index 000000000..4d36b5570
--- /dev/null
+++ b/bit_manipulation/count_of_set_bits.cpp
@@ -0,0 +1,69 @@
+/**
+ * @file
+ * @brief Program to Count set bits in an integer 
+ *
+ * @details
+ * Time Complexity :- O(log n)
+ * Space complexity :- O(1)
+ * @author [Swastika Gupta](https://github.com/swastyy)
+ */
+ 
+#include <cassert>    /// for assert
+#include <iostream>   /// for io operations
+#include <vector>     /// for std::vector
+ 
+/**
+ * @namespace bit_manipulation
+ * @brief bit set counting algorithm
+ */
+namespace bit_manipulation {
+/**
+ * @namespace bitCount
+ * @brief Functions for counting set bits in binary representation of a number
+ */
+namespace bitCount {
+/**
+ * @brief The main function implements set bit count
+ * @param n is the number whose set bit will be counted
+ * @returns count , the number set bit in binary representation of n
+ */
+
+std::uint64_t countSetBits(unsigned int n) {
+    int count = 0; // "count" variable is used to count number of 1's in binary representation of the number
+    while (n!=0) {
+        count += n&1;
+        n=n>>1; // n=n/2 
+    }
+    return count;
+}
+}  // namespace bitCount
+}  // namespace bit_manipulation
+
+/**
+ * @brief Test implementations
+ * @returns void
+ */
+static void test() {
+    // n = 4 return 1
+    assert(bit_manipulation::bitCount::countSetBits(4)==1);
+    // n = 6 return 2
+    assert(bit_manipulation::bitCount::countSetBits(6)==2);
+    // n = 13 return 3
+    assert(bit_manipulation::bitCount::countSetBits(13)==3);
+    // n = 9 return 2
+    assert(bit_manipulation::bitCount::countSetBits(9)==2);
+    // n = 15 return 4
+    assert(bit_manipulation::bitCount::countSetBits(15)==4);
+    // n = 25 return 3
+    assert(bit_manipulation::bitCount::countSetBits(25)==3);
+    std::cout << "All test cases passed" << std::endl;
+}
+
+/**
+ * @brief Main function
+ * @returns 0 on exit
+ */
+int main() {
+    test();  // execute the test
+    return 0;
+}