Solution to https://www.hackerrank.com/challenges/alternating-characters

alternating-characters.js

function processData(input) {
  const lines = input.split('\n')

  // Discard the first line
  lines.shift()

  for (line of lines) {
    // Split line into array of chars
    countMinimumDeletions(line.split(''))
  }
}

function countMinimumDeletions(letters) {
  let deletionCount = 0

  // O(n)
  for (let i = 0; i < letters.length - 1; i++) {
    if (letters[i] === letters[i+1]) {
      deletionCount++
    }
  }
  return deletionCount
}

alternating-characters.md

Example

Input

5 // the number of test cases to evaluate
AAAA
BBBBB
ABABABAB
BABABA
AAABBB

Expected output

3
4
0
0
4