Counting Valleys Solution (Kotlin)

Last week I had some time and I went through one of hackerrank definition which is called counting valley, I tried to write solution in kotlin.

Photo by Fineas Anton on Unsplash

Many of us already know what is hackerrank, if any buddy want to know much about it please visit https://www.hackerrank.com I found it very useful for programmer and do brainstorming practice.

Let’s directly go through problem definition before we went off topic.

Gary is an avid hiker. He tracks his hikes meticulously, paying close attention to small details like topography. During his last hike he took exactly steps. For every step he took, he noted if it was an uphill, , or a downhill, step. Gary’s hikes start and end at sea level and each step up or down represents a unit change in altitude. We define the following terms:

A mountain is a sequence of consecutive steps above sea level, starting with a step up from sea level and ending with a step down to sea level.

A valley is a sequence of consecutive steps below sea level, starting with a step down from sea level and ending with a step up to sea level.

Given Gary’s sequence of up and down steps during his last hike, find and print the number of valleys he walked through.

For example, if Gary’s path is , he first enters a valley units deep. Then he climbs out an up onto a mountain units high. Finally, he returns to sea level and ends his hike.

Function Description

Complete the countingValleys function in the editor below. It must return an integer that denotes the number of valleys Gary traversed.

countingValleys has the following parameter(s):

n: the number of steps Gary takes

s: a string describing his path

Input Format

The first line contains an integer , the number of steps in Gary’s hike.
The second line contains a single string , of characters that describe his path.

Constraints

Output Format

Print a single integer that denotes the number of valleys Gary walked through during his hike.

Sample Input

8
UDDDUDUU

Sample Output

1

Explanation

If we represent _ as sea level, a step up as /, and a step down as \, Gary's hike can be drawn as:

_/\ _
\ /
\/\/

He enters and leaves one valley.

Hopefully you understand the problem definition, before check solution you may give it try to solve it.

Here is the my solution, Please do comments for better solution or you find any mistake in code. Feel free to do so… and don’t forgot if you like the post you always can clap up to 50… I’ll really appreciate it.

fun countingValleys(n: Int, s: String): Int {

    var preCount = 0;
    var count = 0;
    var valley = 0;

    val charArray = s.toCharArray()
    for(i in 0 until s.length){
        if(charArray[i]=='U'){
            count++
        }else if(charArray[i]=='D'){
            count--
        }

        if(count==0 && preCount<count){
            valley++;
        }

        preCount = count;
    }

    return valley;
}

fun main(args: Array<String>) {
    val scan = Scanner(System.`in`)

    val n = scan.nextLine().trim().toInt()

    val s = scan.nextLine()

    val result = countingValleys(n, s)

    println(result)
}

Thank you very much for reading….