Question

unique_list.py] A unique list has no repeated items. For example, the list ['orange', 'juice', 'futures'] is unique because each item only appears one time. However, the list ['sell','mortimer','sell'] is not unique because the string 'sell' appears more than one time.

Write a program named `unique_list` where a user inputs a series of positive integers and, when finished, it reports whether or not the sequence of numbers input is unique or not. For example:

This program tests if the sequence of positive numbers you input are unique
Enter -1 to quit
Enter the first number: 9
Next: 5
Next: 3
Next: 6
Next: 23
Next: -1
The sequence [9, 5, 3, 6, 23] is unique!

This program tests if the sequence of positive numbers you input are unique
Enter -1 to quit
Enter the first number: 83
Next: 20
Next: 593
Next: 28
Next: 20
Next: 51
Next: -1
The sequence [83, 20, 593, 28, 20, 51] is NOT unique!

Answer 1

This code works in python 3. Two implementations of check() are given. You can call any based on time complexities.

Check() runs inO(n²) and check_efficient() runs in O(n) time

def check(test_list):
flag = 0
  
for i in range(len(test_list)):
for i1 in range(len(test_list)):
if i != i1:
if test_list[i] == test_list[i1]:
flag = 1
if(not flag) :
print ("List ",test_list," is unique!")
else :
print ("List",test_list," is NOT unique!")
return   

def check_efficient(test_list):
flag = 0
flag = len(set(test_list)) == len(test_list)
if(not flag) :
print ("List ",test_list," is unique!")
else :
print ("List",test_list," is NOT unique!")
return

#main code
a=[]
print("Enter -1 to quit")
x=int(input("Enter the first number:"))
if x==-1:
print("Empty list not allowed")
exit
a.append(x)
while(1):
x=int(input("Next"))
if x==-1:
check(a) #call check(a) or check_efficient(a)
else:
a.append(x)