Uncompress

Question 1

What’s the problem about?

Answer 1

<number><char> pattern where you will need to repeat the number of char
- sometimes number can be multiple digits
</char></number>

Question 2

What variables or data structures will you use?

Answer 2

• Store result in array instead of concat strings because concat is O(n)
• Create pointer variables start and end

Question 3

What is your approach?

Answer 3

• Create a while loop to run as long as end is less than length of s
• check if index value based on end pointer is a number
  
  • if it is, then increment end pointer
  • if not, slice s to get the num using start and end pointer
  • convert num from string to number
  • loop over num and push string to result array
• increment end pointer
• assign start pointer to end pointer
• return result with join(‘’) method

Question 4

What is the time complexity?

Answer 4

O(n*m)
n = # of groups(number with char)
m = max number for any group(like if we had 1000)

Question 5

What is space complexity?

Answer 5

O(n*m)
- we have to construct that output