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Hash Table Coding Problems

Understand hashing and key-value operations

719
Total Problems
168
Easy
418
Medium
127
Hard
Start Practicing
key → valkey → val

Master DSA Topics - January, 2026

Practice problems across 75+ categories

Hash Table Coding Problems

Practice problems frequently asked at Hash Table • 719 problems | 168 Easy | 418 Medium | 127 Hard

3407Google
3399Amazon
3344Microsoft
2900Meta
571Apple
275Facebook
51Netflix
31Uber
27LinkedIn
17Twitter
15Spotify
14Bloomberg
12Adobe
12Airbnb
11Instagram
9DoorDash
9Lyft
8Goldman Sachs
8Oracle
8ByteDance
# Problem Difficulty Topics
121 Count Substrings That Can Be Rearranged to Contain a String II Hard
Hash TableStringSliding Window
122 Count Substrings That Differ by One Character Medium
Hash TableStringDynamic Programming
123 Count Substrings With K-Frequency Characters I Medium
Hash TableStringSliding Window
124 Count Substrings With K-Frequency Characters II Hard
Hash TableStringSliding Window
125 Count Substrings Without Repeating Character Medium
Hash TableStringSliding Window
126 Count the Number of Beautiful Subarrays Medium
ArrayHash TableBit Manipulation
127 Count the Number of Consistent Strings Easy
ArrayHash TableString
128 Count the Number of Good Partitions Hard
ArrayHash TableMath
129 Count the Number of Good Subarrays Medium
ArrayHash TableSliding Window
130 Count the Number of Good Subsequences Medium
Hash TableMathString
131 Count the Number of Special Characters I Easy
Hash TableString
132 Count the Number of Special Characters II Medium
Hash TableString
133 Count Triplets That Can Form Two Arrays of Equal XOR Medium
ArrayHash TableMath
134 Count Unique Characters of All Substrings of a Given String Hard
Hash TableStringDynamic Programming
135 Count Vowel Substrings of a String Easy
Hash TableString
Showing 121-135 of 719
1 ... 7 8 9 10 11 ... 48

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public class MyFirstJavaProgram { Edit & Run

   /* This is my first java program.
    * This will print 'Hello, World!' as the output
    */

   public static void main(String []args) {
      System.out.println("Hello, World!"); // prints
   }
}

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