added alternatingCharacters hackerrank solution

Author: DevDelvo

hackerRank/alternatingCharacters.js

@@ -0,0 +1,95 @@
+// You are given a string containing characters  and  only. Your task is to change it into a string such that there are no matching adjacent characters. To do this, you are allowed to delete zero or more characters in the string.
+
+// Your task is to find the minimum number of required deletions.
+
+// For example, given the string , remove an  at positions  and  to make  in  deletions.
+
+// Function Description
+
+// Complete the alternatingCharacters function in the editor below. It must return an integer representing the minimum number of deletions to make the alternating string.
+
+// alternatingCharacters has the following parameter(s):
+
+// s: a string
+// Input Format
+
+// The first line contains an integer , the number of queries.
+// The next  lines each contain a string .
+
+// Constraints
+
+// Each string  will consist only of characters  and 
+// Output Format
+
+// For each query, print the minimum number of deletions required on a new line.
+
+// Sample Input
+
+// 5
+// AAAA
+// BBBBB
+// ABABABAB
+// BABABA
+// AAABBB
+// Sample Output
+
+// 3
+// 4
+// 0
+// 0
+// 4
+
+'use strict';
+
+const fs = require('fs');
+
+process.stdin.resume();
+process.stdin.setEncoding('utf-8');
+
+let inputString = '';
+let currentLine = 0;
+
+process.stdin.on('data', inputStdin => {
+  inputString += inputStdin;
+});
+
+process.stdin.on('end', _ => {
+  inputString = inputString.replace(/\s*$/, '')
+    .split('\n')
+    .map(str => str.replace(/\s*$/, ''));
+
+  main();
+});
+
+function readLine() {
+  return inputString[currentLine++];
+}
+
+// Complete the alternatingCharacters function below.
+function alternatingCharacters(s) {
+  let count = 0;
+  for (let i = 0; i < s.length - 1; i++) {
+    let current = s[i];
+    let next = s[i + 1];
+    if (current === next) {
+      count++;
+    }
+  }
+  return count;
+}
+
+function main() {
+  const ws = fs.createWriteStream(process.env.OUTPUT_PATH);
+
+  const q = parseInt(readLine(), 10);
+
+  for (let qItr = 0; qItr < q; qItr++) {
+    const s = readLine();
+
+    let result = alternatingCharacters(s);
+
+    ws.write(result + "\n");
+  }
+
+  ws.end();
+}