Merge pull request #918 from shubhdholakiya/shubh

Power Set using Bit Manipulation

Author: smv1999

Bit Manipulation/Power_Set_using_Bit_Manipulation.cpp

@@ -0,0 +1,53 @@
+/*
+We have to find all elements of power set of given set as string using bit manipulation.
+
+
+Example 1:
+I/p : "sd"
+O/p : "", "s", "d", "sd"
+
+Example 2:
+I/p : "abc"
+O/p : "", "a", "b", "c", "ab", "bc", "ac", "abc"
+
+Formula for Power Set: 2^n , where n is number of elements present in set.
+
+Here, we will be using the formula mentioned above
+in the function printPowerSet. 
+In function printPowerSet Outer function has complexity of 2^n
+and inner funtion has complexity of n.
+So Time Complexity = Theta(2^n * n)
+
+*/
+
+#include<iostream>
+#include<bits/stdc++.h>  // we can also use cmath but bits/stdc++.h is prefered more
+using namespace std;
+
+int printPowerSet(string str)  // function to print all elements of power set
+{
+    int n = str.length();
+    int pow_Size = pow(2, n);
+
+    for (int counter = 0; counter < pow_Size; counter++) // This for loop will run for 2^n times i.e. to find all elements for powerset
+    {
+        for (int j = 0; j < n; j++) // This will run for total n times to print elements where the bit is set.
+        {
+            if ((counter & (1 << j)) != 0) // Check every bit and if bit is set then prints the element of that index.
+            {
+                cout << str[j];
+            }
+        }
+        cout << endl;
+    }
+
+}
+
+int main()
+{
+    string str = "abc";   // string to be passed
+
+    printPowerSet(str);
+
+    return 0;
+}