# Project 1 - Missing Number
# How to find the missing number in an integer array of 1 to 100?
# Trick: 1+2+3+...+n = n(n+1)/2

# Remove some value above to use the function

arr = [ 1,  2,  3,  4,  5,  6,  7,  8,  9, 10,
       11, 12, 13, 14, 15, 16, 17, 18, 19, 20,
       21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 
       31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 
       41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 
       51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 
       61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 
       71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 
       81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 
       91, 92, 93, 94, 95, 96, 97, 98, 99, 100]

def miss_value(list, n):
    sum_n = n*(n+1)/2
    sum_list = sum(list)
    print(f"The missing value is: {sum_n - sum_list}")
    print(f"n(n+1)/2 = {sum_n}")
    print(f"Sum list: {sum_list}")

n = 100
miss_value(arr, n)