leetcode-practices

Jan 1, 2020

1. Two Sum/

• Recurse twice --> O(n^2)
• Could use a Hash Map for better complexity--> O(n)

206. Reverse Linked List/

• Spacial & Temporal Complexity
• Adding a Prev pointer to save "space": Spcial O(1) vs O(n)

903. Valid Permutations for DI Sequence/

• Using python @lru_cache(None)
• using dynamic programming to avoid repeated work

Jan 6, 2020

21. Merge Two Sorted Lists /

• Could implement using recursion
• Could also have O(1) complexity by using pointers

Jan 7, 2020

Similar practices

509. Fibonacci Number
     
510. Climbing Stairs
     
511. Valid Parentheses
     
512. Happy Number/

Jan 20, 2020

892. Surface Area of 3D Shapes:

• Reading the question: be more patient and plug in variables
• parenthesis on pointers while incrementing , debugging by segments
• Using comments smartly
• Using auto keyword/ptrs, vector indexes, syntactic sugar in cpp.
• Problem of 3D shapes: use (sum - touching) rather than six sides(hidden surfaces)