[FIXED] Counting valleys question from hacker rank

Issue

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.

I have tried writing this code in python and it runs well but cannot figure out a code logically

#n is the number of steps and s is the sequence of steps taken

def countingValleys(n, s):

    level=valley=0
    for i in range(n):
        if(s[i]=='U'):
            level+=1
            if(level==0):
                valley+=1
        else:
            level-=1

    return valley

Results are fine

Questions: Can someone explain me the logic starting from if(level==0). If we increase the level by one unit when the person moves uphill, shouldn't we increase valley by 1 then. Why should valley increase by one when level is zero. Confused about the logic- can someone please help me understand this

Solution

Does level=0 valley=0 make any difference, they both are similar level=valley=0

The logic is simple you just have to count if the no if "U"-uphill assigned as '1' and number of 'D'-Downhills assigned as '-1' and on adding the both count one should get '0' as in [DDDUUU] which will increment valley by '1'.

Answered By - Pawan