File20. Дан файл вещественных чисел. Найти общее количество его локальных экстремумов, то есть локальных минимумов и локальных максимумов (определения локального минимума и локального максимума даны в заданиях File18 и File19).

Решение на Python 3:

import random

def GenerateLine(fname):
    N = random.randrange(1,10)
    print("N = ",N)
    #N = 2
    #line = "1, 5, 5, 5, 4, 4, 5"
    try:
        f = open(fname, "w")
        try:
            for i in range(N):
                line = str(random.randint(1,4))+"\n"
                f.write(line)
        finally:
            f.close()
    except IOError:
        print('Write error: ',fname)

f_input = "file20_input.txt"
#GenerateLine(f_input)

unique_num = 0
extr_num = 2
try:
    with open(f_input,'r') as f_in:
        for line in f_in:
            x = int(line.strip())
            print(x)

            if unique_num > 0 and x == x_prev:
                #print(" : skipped")
                continue
            
            x_prev = x
            unique_num += 1
            if unique_num == 1:
                x1 = x
            elif unique_num == 2:
                x2 = x
            elif unique_num == 3:
                x3 = x
                #print("hello: {0},{1},{2}".format(x1,x2,x3))
                if (x1 < x2 and x2 > x3) or (x1 > x2 and x2 < x3):
                    extr_num += 1
            else:
                x1 = x2
                x2 = x3
                x3 = x
                if (x1 < x2 and x2 > x3) or (x1 > x2 and x2 < x3):
                    extr_num += 1
            #print(":",extr_num,":",unique_num)

except IOError:
    print('Open error: ',f_source)

print("unique_num: ",unique_num)

if unique_num == 1:
    extr_num = 1
elif unique_num == 2:
    extr_num = 2
    
print("Number of local extremums:",extr_num)