A = [45, 17, 28, 34, 100] 
i = 0         
nmin = i      
min = a[nmin] 
nmax = i      
max = a[nmax] 
while (i < len(a)):
    if (a[i] < min):
        nmin = i
        min = a[nmin]
    if (a[i] > max):
        nmax = i
        max = a[nmax]
    i += 1
print "min = a[", nmin, "] = ", min
print "max = a[", nmax, "] = ", max

From random import random
N = 10
a = []
for i in range(N):
    b = int(random() * 50)
    a.append(b)
print(a)

min = a[0]
max = a[0]
for i in range(N):
     if (a[i] < min):
          min = a[i]     if a[i]>max:
          max = a[i]print('min = ',min)
print('max = ',max)

Пример:
[48, 12, 44, 48, 32, 1, 10, 37, 42, 21]
min = 1
max = 48