338.Counting Bits (Sept.1)

Author: SjxSubham

338.Counting Bits

@@ -0,0 +1,35 @@
+/*Explanation
+1. we are iterating till n;
+	for every i, we have to count 1's bits in its binary form.
+	0 --> 0
+	1 --> 1
+	2 --> 10
+	3 --> 11
+	4 --> 100
+	5 --> 101
+	
+	Output: [0,1,1,2,1,2]
+  */
+class Solution {
+public:
+// T.C - o(nlog n)
+    vector<int> countBits(int n) {
+        vector<int>ans;
+        //loop ko 0 se n tak chalayenge
+        for(int i=0;i<=n;i++){
+            // sum is initialized as zero
+            int sum =0;
+            int num =i;
+            //while num not equals zero
+            while(num != 0){
+                //we have to count '1' s in binary representation of i, there fore % 2
+                sum += num%2;
+                num = num/2;
+            }
+            //add sum to ans vector
+            ans.push_back(sum);
+        }
+        //return 
+        return ans;
+    }
+};