Any sequence of integers consisting of strictly decreasing values followed by strictly increasing values such that the decreasing and increasing sequence have a minimum length of 2 and the last value of decreasing sequence is the first value of the increasing sequence is said to be a Valley.

The sequence [ 4, 3. 2, 1, 2, 3, 4] is an example of a Valley. In this article, we will create a Python Program to check wheater the given sequence is a valley or not.

Python Program To Check Whether The Given List Is Valley Or Not

def valley(l):
    if (len(l) < 3):
        return False

    up_count = 1
    low_count = 1

    for i in range(0, len(l) - 1):
        if l[i] > l[i + 1]:
            if low_count > 1:
                return False
            up_count = up_count + 1
        if l[i] < l[i + 1]:
            low_count = low_count + 1
        if l[i] == l[i + 1]:
            return False

    if up_count > 1 and low_count > 1:
        return True
    else:
        return False

print(valley([3, 2, 8, 1, 2, 3]))

print(valley([3, 2, 1, 2, 3]))

Output:

False
True