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Leetcode Problem 232. Implement Queue using Stacks

232. Implement Queue using Stacks

Leetcode Solutions

Approach # (Two Stacks) Push - O() per operation, Pop - Amortized O() per operation

  1. Initialize two stacks, s1 and s2.
  2. For push operation, push the element onto s1.
  3. For pop operation, if s2 is empty, transfer all elements from s1 to s2 by popping from s1 and pushing onto s2. Then pop the top of s2.
  4. If s2 is not empty, pop the top of s2 directly.
  5. For peek operation, if s2 is empty, transfer all elements from s1 to s2 and return the top of s2. If s2 is not empty, return the top of s2.
  6. For empty operation, check if both s1 and s2 are empty. If both are empty, the queue is empty.
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Approach # (Two Stacks) Push - O(n) per operation, Pop - O() per operation

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