Searching Algorithms

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Practice Problems on Searching Algorithms
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What is Searching Algorithm?

Searching Algorithms are designed to check for an element or retrieve an element from any data structure where it is stored.

Based on the type of search operation, these algorithms are generally classified into two categories:

1. Sequential Search: In this, the list or array is traversed sequentially and every element is checked. For example: Linear Search.

   Linear Search to find the element “20” in a given list of numbers

   

   Linear-Search

2. Interval Search: These algorithms are specifically designed for searching in sorted data-structures. These type of searching algorithms are much more efficient than Linear Search as they repeatedly target the center of the search structure and divide the search space in half. For Example: Binary Search.

   Binary Search to find the element “23” in a given list of numbers

   

   Binary Search

Topic :

Searching Algorithm:

1. Linear Search
2. Sentinel Linear Search
3. Binary Search
4. Meta Binary Search | One-Sided Binary Search
5. Ternary Search
6. Jump Search
7. Interpolation Search
8. Exponential Search
9. Fibonacci Search
10. The Ubiquitous Binary Search

Comparisons:

1. Linear Search vs Binary Search
2. Interpolation search vs Binary search
3. Why is Binary Search preferred over Ternary Search?
4. Is Sentinel Linear Search better than normal Linear Search?

Library Implementations of Searching Algorithms :

1. Binary Search functions in C++ STL (binary_search, lower_bound and upper_bound)
2. Arrays.binarySearch() in Java with examples | Set 1
3. Arrays.binarySearch() in Java with examples | Set 2 (Search in subarray)
4. Collections.binarySearch() in Java with Examples

Some standard problems on Searching:

• Easy:
  1. Find the largest three elements in an array
  2. Find the Missing Number
  3. Find the first repeating element in an array of integers
  4. Find the missing and repeating number
  5. Search, insert and delete in a sorted array
  6. Count 1’s in a sorted binary array
  7. Two elements whose sum is closest to zero
  8. Find a pair with the given difference
  9. k largest(or smallest) elements in an array
  10. Kth smallest element in a row-wise and column-wise sorted 2D array
  11. Find common elements in three sorted arrays
  12. Ceiling in a sorted array
  13. Floor in a Sorted Array
  14. Find the maximum element in an array which is first increasing and then decreasing
  15. Given an array of of size n and a number k, find all elements that appear more than n/k times
• Medium:
  1. Find all triplets with zero sum
  2. Find the element before which all the elements are smaller than it, and after which all are greater
  3. Find the largest pair sum in an unsorted array
  4. K’th Smallest/Largest Element in Unsorted Array
  5. Search an element in a sorted and rotated array
  6. Find the minimum element in a sorted and rotated array
  7. Find a peak element
  8. Maximum and minimum of an array using minimum number of comparisons
  9. Find a Fixed Point in a given array
  10. Find the k most frequent words from a file
  11. Find k closest elements to a given value
  12. Given a sorted array and a number x, find the pair in array whose sum is closest to x
  13. Find the closest pair from two sorted arrays
  14. Find three closest elements from given three sorted arrays
  15. Binary Search for Rational Numbers without using floating point arithmetic
• Hard:
  1. Median of two sorted arrays
  2. Median of two sorted arrays of different sizes
  3. Search in an almost sorted array
  4. Find position of an element in a sorted array of infinite numbers
  5. Given a sorted and rotated array, find if there is a pair with a given sum
  6. K’th Smallest/Largest Element in Unsorted Array | Worst case Linear Time
  7. K’th largest element in a stream
  8. Best First Search (Informed Search)

Quick Links:

1. ‘Practice Problems’ on Searching
2. ‘Quizzes’ on Searching

Recomended:

• Learn Data Structure and Algorithms | DSA Tutorial

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