Two Pointer Problem Categories
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Two Pointer Problem Categories

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Questions and Answers

Which method is commonly used for detecting cycles in a linked list?

  • Merge sort
  • Stack method
  • Recursion
  • Two-pointer approach (correct)

    • The sliding window technique can be used to find a maximum value in an array.

    True

    What is the primary purpose of the 'remove duplicates' operations in arrays?

    To eliminate repeated elements and reduce the size of the dataset.

    The two-pointer technique is typically used to traverse a linked list or an array by employing a ____ pointer and a ____ pointer.

    <p>fast, slow</p> Signup and view all the answers

    Match the problem to its corresponding technique:

    <p>Linked List Cycle = Two-pointer Remove Duplicates from Sorted Array = Array Manipulation Find the Duplicate Number = Cyclic Detection Number of Subarrays with Bounded Maximum = Sliding Window</p> Signup and view all the answers

    What does the 'rotate list' problem involve?

    <p>Shifting nodes to the right by k places</p> Signup and view all the answers

    Cyclic detection can be performed only with linked lists.

    <p>False</p> Signup and view all the answers

    What is a common application of the sliding window method in problem-solving?

    <p>Finding the maximum or minimum sum of a contiguous subarray.</p> Signup and view all the answers

    Which of the following algorithms is primarily used for merging two sorted arrays?

    <p>Two Pointers</p> Signup and view all the answers

    All substring problems can be solved using the sliding window technique.

    <p>False</p> Signup and view all the answers

    What is the purpose of the find-median-from-data-stream problem?

    <p>To find the median of a continuously incoming data stream.</p> Signup and view all the answers

    The operation of __________ involves detecting cycles in a linked list.

    <p>cyclic detection</p> Signup and view all the answers

    Which problem involves partitioning an array to minimize the sum difference?

    <p>Partition Array into Two Arrays to Minimize Sum Difference</p> Signup and view all the answers

    Match the following problems with their appropriate categories:

    <p>Partition List = Split &amp; Merge of an array / Divide &amp; Conquer Sort List = Sorting Intersection of Two Linked Lists = Intersections/LCA like Find Median from Data Stream = Median Finder</p> Signup and view all the answers

    Which technique is typically used to solve problems involving finding unique or common elements in arrays?

    <p>Hashing</p> Signup and view all the answers

    The two-pointer technique can only be applied to sorted arrays.

    <p>False</p> Signup and view all the answers

    What is the primary purpose of the two-pointer technique in algorithms?

    <p>To traverse an array from both ends toward the center</p> Signup and view all the answers

    The Trapping Water problem can be solved using the two-pointer technique.

    <p>True</p> Signup and view all the answers

    Name one problem that utilizes the slow and fast pointer technique.

    <p>Cyclic Detection</p> Signup and view all the answers

    The problem involving determining the __________ of elements that meet a specified sum condition is part of the two-pointer category.

    <p>number</p> Signup and view all the answers

    Match the following two-pointer techniques with their applications:

    <p>Running from both ends = Finding pairs in arrays with a specific sum Sliding Window = Finding subarrays with a given sum Slow &amp; Fast Pointers = Detecting cycles in lists Reversing/Swapping = Rearranging characters in strings</p> Signup and view all the answers

    Which of the following is NOT a category associated with the two-pointer technique?

    <p>Dynamic Programming</p> Signup and view all the answers

    The problem of minimizing the maximum pair sum requires a clear understanding of array manipulation.

    <p>True</p> Signup and view all the answers

    What common misconception might someone have about the usage of two pointers?

    <p>That it can only be applied to sorted arrays.</p> Signup and view all the answers

    The __________ is a common example of a problem solved using the two-pointer approach to find an optimal arrangement.

    <p>Next Permutation</p> Signup and view all the answers

    Which problem is typically used as an example to illustrate the concept of running two pointers from both ends?

    <p>Two Sum</p> Signup and view all the answers

    Study Notes

    Two Pointer Problem Categories and Examples

    • Two pointer problems are common in technical interviews, and there are around 140 problems on LeetCode.
    • The majority of these problems are easy or medium difficulty.
    • The notes categorize the 117 solved LeetCode problems into four main categories.

    Running from Both ends of an Array

    • Two pointers start at the beginning and end of the array and move towards the center.
    • Example problems:
      • Two Sum II - Input Array is Sorted
      • Trapping Rain Water
      • Next Permutation
      • Reverse String

    Slow & Fast Pointers

    • Two pointers move at different speeds, typically from the left end.
    • The fast pointer provides information to the slow pointer for processing.
    • Example problem categories :
      • Linked List Operations
      • Cyclic Detection
      • Sliding Window/Caterpillar Methods
      • Rotation
      • String Manipulation
      • Remove Duplicates

    Running from Beginning of 2 Arrays/Merging 2 Arrays

    • Involves two pointers iterating through two given arrays or lists.
    • Example problem categories:
      • Sorted Arrays
      • Intersections/LCA-like
      • Substring
      • Median Finder
      • Meet-in-the-middle/Binary Search

    Split & Merge of the Array/Divide & Conquer

    • First, split the given list into two separate lists, then apply two pointers to merge or unify them.
    • Example problem categories:
      • Partition
      • Sorting

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    Related Documents

    2pointer-article -leetcode.pdf

    Description

    Explore the main categories of two pointer problems commonly encountered in technical interviews. This quiz covers a range of examples from various problem types like running from both ends of an array and using slow & fast pointers. Test your knowledge and understanding of these effective problem-solving techniques.

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