#
# Nested loops 
#
# Practice 
# 

# Preliminary notes: 
- Presumed knowledge:
  - That practiced in pervious videos 
  - Basic structure of strings, lists
  - for loop 
  - The functions range(), length(), eval() 
  - The operators in, *, + 
  - Iterative consturction of strings and lists 
- Relation to tuples 
- Use only the studied material.
  In particular do not use type functions 



# Q. 1
# Write a program that receives a positive integer n, 
# and then prints a triangle with the following strucutre: 
# 1...n 
# 1..n-1
# ... 
# 12 
# 1 
# E.g. if n == 5 the program prints: 
# 12345
# 1234
# 123
# 12
# 1

n = int("Please enter a positive integer: ")
#n = 9
lst = list(range(1, n + 1))
[1, 2, 3, 4, 5]
 0  1  2  3  4 
for i in range(n):
    for num in range(1, n + 1 - i): 
        print(num, end = "")
    print() 

12345  i = 0 range(1, n + 1)
1234   i = 1 range(1, n + 1 - i) 
123    i = 2 range(1, n + 1 - i)
12     i = 3 range(1, n + 1 - i)
1      i = 4 range(1, n + 1 - i)


for i in range(n):
    for num in range(1, n + 1): 
        print(num, end = "")
    print() 




line = ""
for num in lst: 
    line = line + str(num)
print(line)








Q. 2
Write a program that receives a positive integer n, 
and then prints a triangle with the following strucutre: 
n.....1
n-1..1
... 
21 
1 
E.g. if n == 5 the program prints: 
54321
5432
543
54
5


# solution 1 
#n = int("Please enter a positive integer: ")
#n = 9
for i in range(n): 
    line = ""
    for num in range(1 + i, n + 1): 
        line = str(num) + line
    print(line)


# solution 2
n = int("Please enter a positive integer: ")
#n = 9
for i in range(n):
    for num in range(n, i, -1): 
        print(num, end = "")
    print() 


range(3)
range(1, 7)
print(list(range(3,  10, 4)))
print(list(range(10,  3, -4)))






# Q. 3
# Write a program that receives a positive integer n
# greater than 1, and prints all pairs of positive integers whose 
# sum is n. Each pair is printed once, and in each 
# printed pair, the first integer is smaller 
# than the second or equal to it. 
# E.g. if n == 6 the program prints
# 1 5 
# 2 4 
# 3 3 
# Challenge: do the same for triples, 
# e.g. if n == 6 the program prints: 
# 1 1 4
# 1 2 3
# 2 2 2  
 

1...n-l
1...5 
n = 6
for i in range(1, n): 
    for j in range(1, n):        
        if i <= j and i + j == n: 
            print(i, j)




    
# Q. 4
# Write a program that receives an integer comprised
# of three or more digits, and prints the two digits
# whose difference one from the other is the biggest. 
# Assume there are only two such digits and that 
# they appear anywhere in the integer. 


num = input("Please enter an integer greater than 99: ")
#num = "74539"
maxDiff = 0 
for digit1 in num: 
    for digit2 in num: 
        if maxDiff < abs(int(digit1) - int(digit2)): 
            maxDiff = abs(int(digit1) - int(digit2))
            pair1 = digit1 
            pair2 = digit2 
print(pair1, pair2 )
        




# Q. 5
# Write a program that receives a non-empty list 
# of numbers and prints True if no number 
# appears in the list more than once, False 
# otehrwise. 


# lst = eval(input("Please enter a non-empty list: "))
lst = [5, 5, 3, 2, 6, 7, 7]
result = True 
for num1 in lst: 
    counter = 0 
    for num2 in lst: 
        if num2 == num1: 
            counter = counter + 1
    if counter > 1: 
        result = False 
print(result)



# Q. 6 
# Write a program tha produces 10 samples 
# of size 5 from the range 1:20, without revieion. 


import random 
for i in range(10): 
    mySample = [] 
    while len(mySample) < 5: 
        randNum = random.randint(1, 20)
        if randNum not in mySample: 
            mySample = mySample + [randNum]
    print(mySample)