Added Counting-Valleys problem solution

Author: ParrotStone

Counting Valleys/main.js

@@ -0,0 +1,24 @@
+#!/usr/bin/env node
+
+// Problem Description at -> https://www.hackerrank.com/challenges/counting-valleys/problem
+
+function countingValleys(n, s) {
+ let valleysCount = 0;
+ let seaLevel = 0;
+
+ for (let i = 0; i < n; i++) {
+ if (s[i] == 'D') seaLevel--;
+ if (s[i] == 'U') seaLevel++;
+ // Check if we just came from a valley up to sea level
+ if (!seaLevel && s[i] == 'U') valleysCount++;
+ }
+
+ return valleysCount;
+}
+
+// // Test cases
+// console.log(countingValleys(8, 'UDDDUDUU')); // 1
+// console.log(countingValleys(8, 'UDUDUDUDU')); // 0, since there is no vallies crossed...
+// console.log(countingValleys(8, 'DDDUUUDDU')); // 1
+console.log(countingValleys(8, 'DDUUUUDD')); // 1
+