add codeforces solutions folder

leetcode/lc868.cpp

@@ -0,0 +1,18 @@
+class Solution{
+    public : 
+        int binaryGap(int n){
+            int last = -1;
+            int ans =0;
+            for(int i =0;i<32;i++){
+                if(n>>i & 1){
+                    if(last!=-1)
+                        ans = max(ans, i-last);
+                    last = i;
+                }
+            }
+            return ans;
+        }
+};
+//We'll store last, the index of the last set bit encountered. If n has the ith bit set, answer is i - last, and then the new last value would be last = i.
+//TC : o(logn) , logn is the number of digits in the binary representation of n 
+//SC : o(1)