Step 1. i/p= “wwwwaaadexxxxxx”

Step 2. converted= {'w': 4, 'a': 3, 'd': 1, 'e': 1, 'x': 6}

Step Final. o/p= 'w4a3d1e1x6'

I'm on S2 how to go to final step ?

Would appreciated direct conversions 1-> Final

Time Complexity should be less but would appreciate any Sol.

I want to return in form of String stored in any var

without importing anything

You could use a comprehension(But you need to convert those numbers to string), Try code below:

converted = {'w': 4, 'a': 3, 'd': 1, 'e': 1, 'x': 6}
print("".join([str(char) for k, v in converted.items() for char in (k, v)]))