Counting Valleys | HackerRank

 An avid hiker keeps meticulous records of their hikes. During the last hike that took exactly  steps, for every step it was noted if it was an uphill, , or a downhill,  step. Hikes always 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 the sequence of up and down steps during a hike, find and print the number of valleys walked through.

Example

 

The hiker first enters a valley  units deep. Then they climb out and up onto a mountain  units high. Finally, the hiker returns to sea level and ends the hike.

Function Description

Complete the countingValleys function in the editor below.

countingValleys has the following parameter(s):

• int steps: the number of steps on the hike
• string path: a string describing the path

Returns

• int: the number of valleys traversed

Input Format

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

Constraints

Sample Input

8
UDDDUDUU

Sample Output

1

Explanation

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

_/\                  _
           \           /
              \/\/

The hiker enters and leaves one valley.

SOLUTION IN C#

using System.CodeDom.Compiler;

using System.Collections.Generic;

using System.Collections;

using System.ComponentModel;

using System.Diagnostics.CodeAnalysis;

using System.Globalization;

using System.IO;

using System.Linq;

using System.Reflection;

using System.Runtime.Serialization;

using System.Text.RegularExpressions;

using System.Text;

using System;

class Result

{

    public static int countingValleys(int steps, string path)

    {

        int next = 0;

        int previous = 0;

        int valleys = 0;

        for(int i = 0; i < steps; i++){

            if(path[i] == 'U'){

                previous = next;

                next++;                

            }else{

                previous=next;

                next--;

            }

            if(previous < 0 && next == 0){

                valleys++;

            }

        }

        return valleys;

    }

}

class Solution

{

    public static void Main(string[] args)

    {

        TextWriter textWriter = new StreamWriter(@System.Environment.GetEnvironmentVariable("OUTPUT_PATH"), true);

        int steps = Convert.ToInt32(Console.ReadLine().Trim());

        string path = Console.ReadLine();

        int result = Result.countingValleys(steps, path);

        textWriter.WriteLine(result);

        textWriter.Flush();

        textWriter.Close();

    }

}