Added a bit manipulation programs

Bit Manipulation/maximizing_bits.cpp

@@ -0,0 +1,41 @@
+// C++ program to find maximum number by 
+// swapping extreme bits. 
+#include <bits/stdc++.h> 
+using namespace std; 
+
+#define ull unsigned long long int 
+
+ull findMax(ull num) 
+{ 
+    ull num_copy = num; 
+
+    /* Traverse bits from both extremes */
+    int j = sizeof(unsigned long long int) * 8 - 1; 
+    int i = 0; 
+    while (i < j) { 
+
+        // Obtaining i-th and j-th bits 
+        int m = (num_copy >> i) & 1; 
+        int n = (num_copy >> j) & 1; 
+
+        /* Swapping the bits if lesser significant 
+           is greater than higher significant 
+           bit and accordingly modifying the number */
+        if (m > n) { 
+            int x = (1 << i | 1 << j); 
+            num = num ^ x; 
+        } 
+
+        i++; 
+        j--; 
+    } 
+    return num; 
+} 
+
+// Driver code to run program
+int main() 
+{ 
+    ull num = 4; 
+    cout << findMax(num); 
+    return 0; 
+}