Day-30: More Bit manipulation problems

Author: mandliya

README.md

@@ -4,9 +4,9 @@
 
 | Current Status|     Stats     |
 | :------------: | :----------: |
-| Total Problems | 43 |
-| Current Streak | 29 |
-| Longest Streak | 29 ( August 17, 2015 - September 14, 2015 ) |
+| Total Problems | 46 |
+| Current Streak | 30 |
+| Longest Streak | 30 ( August 17, 2015 - September 15, 2015 ) |
 
 </center>
 
@@ -52,7 +52,9 @@ Include contains single header implementation of data structures and some algori
 | Find the parity of given number. | [find_parity.cpp](bit_manipulation/find_parity.cpp) |
 | Implement fast multiplication of a number to 7 using bit manipulation. | [multiply_by_7.cpp](bit_manipulation/multiply_by_7.cpp) |
 | Reverse bits of unsigned integer (two methods - Reversing bit by bit & divide and conquer). | [reverseBitsOfAnInteger.cpp](bit_manipulation/reverseBitsOfAnInteger.cpp) |
-
+| Small function to determine position of right most set bit in a given integer.| [right_most_set_bit.cpp](bit_manipulation/right_most_set_bit.cpp)| 
+|Given a vector of numbers, only one number occurs odd number of times, find the number.| [find_odd_one_out.cpp](bit_manipulation/find_odd_one_out.cpp)|
+| Given two integers, determine if their sum would be interger overflow.| [integerOverflow.cpp](bit_manipulation/integerOverflow.cpp)|
 ### Cracking the coding interview problems
 | Problem | Solution |
 | :------------ | :----------: |

bit_manipulation/find_odd_one_out.cpp

@@ -0,0 +1,37 @@
+/**
+ *  Given a vector of numbers, only one number occurs odd number of times, find the number
+ *  Example - { 1, 1, 2, 2, 2, 3, 3, 3, 3} ==> Answer 3
+ *  Approach - XOR of number with itself is 0, so even numbers will cancel out
+ *  and we will be left with odd number.
+ */
+
+#include <iostream>
+#include <vector>
+
+int find_odd_one_out( const std::vector<int> & vec )
+{
+  int check = 0;
+  for ( auto i : vec )
+  {
+    check ^= i;
+  }
+  return check;
+}
+
+void printVector( const std::vector<int> & vec )
+{
+  for ( auto & i : vec ) {
+    std::cout << i << " ";
+  }
+  std::cout << std::endl;
+}
+
+int main()
+{
+  std::vector<int> vec{2, 3, 5, 4, 5, 2, 4, 3, 5, 2, 4, 4, 2};
+  std::cout << "Vector contains :" << std::endl;
+  printVector( vec );
+  std::cout << "Number which occurs odd time in the above vector :"
+            << find_odd_one_out( vec ) << std::endl;
+  return 0;
+}

bit_manipulation/integerOverflow.cpp

@@ -0,0 +1,32 @@
+/**
+ *  Given two integers, determine if their sum would be interger overflow.
+ */
+
+#include <iostream>
+
+/**
+ * Integer overflow check
+ * @param  a [an Integer]
+ * @param  b [another Integer]
+ * @return   [returns true if a + b causes Integer overflow]
+ */
+bool integerOverflow( int a, int b)
+{
+    int c = a + b;
+    if ( a > 0 && b > 0 && c < 0 ) {
+        return true;
+    } else if ( a < 0 && b < 0 && c > 0 ) {
+        return true;
+    }
+    else {
+        return false;
+    }
+}
+
+int main()
+{
+    int x = 2147483640;
+    int y = 10;
+    std::cout << "Sum of " << x << " and " << y << " causes interger overflow :"
+              << (integerOverflow( x, y ) ? "true\n":"false\n");
+}

bit_manipulation/right_most_set_bit.cpp

@@ -0,0 +1,26 @@
+/**
+ *  Problem : One line function to return the position of right most bit.
+ *  Approach : take 2's compliment and it with number.
+ *  And finally taking a log of 2  + 1 will give us the positon
+ */
+
+#include <iostream>
+#include <cmath>
+
+int position_of_first_set_bit( int num )
+{
+  return log2(num & -num) + 1;
+}
+
+int main()
+{
+  int num;
+  std::cout << "Enter a number :";
+  std::cin >> num;
+
+  std::cout << "Position of first set bit number in binary representation of "
+            << num << " is " << position_of_first_set_bit( num )
+            << std::endl;
+
+  return 0;
+}