Inorder Level order Cyclic Counter problem real time data is coming in, when a function “middle” is called the middle element has to be returned. Also use suitable data structure to store the data. Given str s1 and s2 Find if s2 is a substring If so reverse s2 and change it in place in str s1 Perfect number(3+2+1=6) Diamond problem of multiple inheritance How does heap sort using List comprehension execute 10 times faster than normal heap sort Iterator and generator Three sum- Given an array, if sum of three elements of the array is 0 return those three elements