Leetcode 476

Author: kalpak92

LeetCode/476. Number Complement/main.cpp

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+#include <iostream>
+#include "solution.h"
+using namespace std;
+
+int main()
+{
+    Solution s;
+    cout << s.findComplement(76) << endl;
+
+    return 0;
+}

LeetCode/476. Number Complement/solution.h

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+/*
+**  Given a positive integer, output its complement number. 
+**  The complement strategy is to flip the bits of its binary representation.
+**
+**  Note:
+**  The given integer is guaranteed to fit within the range of a 32-bit signed integer.
+**  You could assume no leading zero bit in the integer’s binary representation.
+**  Example 1:
+**  Input: 5
+**  Output: 2
+**  Explanation: The binary representation of 5 is 101 (no leading zero bits), and its complement is 010. So you need to output 2.
+**  Example 2:
+**  Input: 1
+**  Output: 0
+**  Explanation: The binary representation of 1 is 1 (no leading zero bits), and its complement is 0. So you need to output 0.
+*/
+#include <iostream>
+
+using namespace std;
+
+class Solution
+{
+    public:
+    /*
+    *   We need to flip each bit, but the starting position of the flip starts from the highest bit of 1, 
+    *   and the front 0 cannot be flipped.
+    *   So we go from high to low traversal, if the first one is encountered, our flag is assigned to true, 
+    *   and then it can be flipped.
+    */
+    int findComplement(int num)
+    {
+        if (num == 1)
+            return 0;
+
+        bool flag = false;
+
+        for (int i = 31; i >= 0; i--)
+        {
+            if(num & (1 << i))
+                flag = true;
+            if(flag)
+                num ^= (1 << i);
+        }
+        return num;
+    }
+};