Lesson overview · Free interview practice

Two Pointers

Solve problems using two pointers to traverse arrays.

Topics in the full lesson
  • Concept and Use Cases
  • When to Use
  • Time and Space Complexity
  • Pair with Target Sum in a Sorted Array
  • Removing Duplicates from a Sorted Array
  • Checking if a String is a Palindrome

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CodingEasy

Squares of a Sorted Array

Question

Given an integer array nums sorted in non-decreasing order, return an array of the squares of each number, sorted in non-decreasing order. Solve in O(n) using two pointers.

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Explain your reasoning or try an implementation before comparing answers.

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CodingEasy

Valid Palindrome II

Question

Given a string s, return true if it can be made a palindrome by deleting at most one character; otherwise return false.

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Explain your reasoning or try an implementation before comparing answers.

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CodingMedium

3Sum

Question

Given an array of integers, find all unique triplets that sum to zero.

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Explain your reasoning or try an implementation before comparing answers.

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