LeetCode Club First Contest

What's the time complexity of the two-pointer approach in LeetCode 125 (Valid Palindrome)? 

• O(n) 

• O(n^2)

• O(log n)

• O(1)

Select all the the space complexity if it’s indicates that the memory requirement grows with the total size of >= input.

• O(1), O(n^2) , O(n - m)

• O(2n), O(m+n) , O(1)

• O(m+n), O(n)

• O(max(m,n)), O(1)

Which of the following is NOT a valid way to reverse a string in Python? 

• s[::-1]

•  .join(reversed(s)) 

• s.reverse() 

• join(s[i] for i in range(len(s)-1, -1, -1))

In the context of the LeetCode 121 problem, which statement about the algorithm's approach to finding the maximum profit is most accurate

• The algorithm only considers the stock prices on the days when the maximum profit occurs.
  

• The algorithm relies on updating both min_price and max_profit simultaneously as it iterates through the stock prices.
  

• The algorithm uses a nested loop to compare every possible buy-sell pair, leading to a time complexity of O(n²).
  

• The algorithm assumes that stock prices can only increase, leading to potential inaccuracies in profit calculation.

What's the time complexity of the optimized solution for LeetCode 122 (Best Time to Buy and Sell Stock II) (1 loop)? 

• O(n)

• O(n^2)

• O(log n)

• O(n log n)

In many Linked List Problems, what's the purpose of the dummy node?

• To simplify edge cases

• To improve time complexity

• To reduce space complexity

• To reverse the linked list

What's the space complexity of the Floyd's Cycle-Finding Algorithm used in LeetCode 141 (Linked List Cycle)? 

• O(1)

• O(n) 

• O(log n)

• O(n^2)

to reverse a single Linked List) what's the correct order of pointer updates in the iterative solution? 

• current.next = previous, previous = current, current = forward, forward = previous

• current = forward, previous = current, current.next = previous, current = current.next

• forward = current.next, current.next = previous, previous = current, current = forward

• previous = current, current = forward, forward = current.next, current.next = previous

What Data Structure you can use to solve this question?

• Stack

• Tree

• List

• Queue

In LeetCode 739 (Daily Temperatures), what does the stack typically store? 

def dailyTemperatures(self, temps: List[int]) -> List[int]:

result = [0] * len(temps)

stack = []

for ...... in enumerate(temps):

while stack and stack[-1][0] < t:

........ = stack.pop()

result[si]= i - si

stack.append(............)

return result

• Tuples of temperatures and associate index

•  Days until it gets warmer

• Indices of a warmer day

• Temperature differences between two days