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Grokking the Coding Interview Patterns in Go

Solution: Number of Wonderful Substrings

Explore the solution to counting wonderful substrings where at most one character appears an odd number of times. Learn how to use hash maps and bitmasks to track character frequencies and efficiently solve substring problems in Go. This lesson enhances your ability to apply data structures for optimized coding interview solutions.

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Statement

A wonderful string is defined as a string in which at most one letter occurs an odd number of times.

For example:

  • The string “aabbc” is wonderful because only the letter 'c' appears an odd number of times.

  • The string “pqpq” is wonderful because all letters appear an even number of times.

  • The string “mn” is not wonderful because both 'm' and 'n' appear an odd number of times.

You are given a string word that consists of lowercase English letters from 'a' to 'j'. Your task is to return the total number of wonderful non-empty substringsA substring is any contiguous sequence of characters within the string. in word.

Note: If a substring appears multiple times, each occurrence should be counted separately.

Constraints: ...