Added day28 solution

Author: avidLearnerInProgress

30-days-of-code-may/28.countingBits.cpp

@@ -0,0 +1,8 @@
+class Solution {
+public:
+    vector<int> countBits(int num) {
+        vector<int> bits(num+1, 0);
+        for(int i = 1; i <= num; i++) bits[i] += bits[i>>1] + i&1;
+        return bits;   
+    }
+};