Five programming problems every Software Engineer should be able to solve in less than 1 hour

a.py

def sum_of_for(li):
    s = 0
    for l in li:
        s += l
    return s

def sum_of_while(li):
    s = 0
    i = 0
    while i < len(li):
        s += li[i]
        i += 1
    return s

def sum_of_rec(li):
    if len(li) == 0:
        return 0
    else:
        e = li.pop()
        return sum_of_rec(li) + e
        
if __name__ == '__main__':
    li = [1, 2, 3, 4, 5]
    print(sum_of_for(li))
    print(sum_of_while(li))
    print(sum_of_rec(li))

b.py

def merge(x, y):
    ret = []
    m = len(x) if len(x) > len(y) else len(y)
    for i in range(m):
        if i < len(x):
            ret.append(x[i])
        if i < len(y):
            ret.append(y[i])
    return ret

if __name__ == '__main__':
    x = ['a', 'b', 'c', 'd', 'e']
    y = ['1', '2', '3', '4']
    print(merge(x, y))

c.py

def sum_of_fib(n=100):
    fib = [0, 1]
    s = 1
    for i in range(2, n):
        fib.append(fib[i-1] + fib[i-2])
        s += fib[i]
        i += 1
    return s

if __name__ == '__main__':
    print(sum_of_fib())

d.py

from functools import cmp_to_key

def cmp(a, b):
    if a == b: return 0
    return -1 if a < b else 1

def mycomp(x, y):
    sx = str(x)
    sy = str(y)
    return cmp((sx + sy) , (sy + sx))

def max_num(lst):
    lst = sorted(lst, key=cmp_to_key(mycomp))
    ret = ""
    for i in reversed(lst):
        ret += str(i)
    return ret

if __name__ == '__main__':
    lst = [50, 2, 1, 9]
    print(max_num(lst))

e.py

import itertools

def one_hundred():
    lst = range(1,10)
    for calc in itertools.product('+- ', repeat=8):
        s = []
        for i,c in enumerate(calc):
            s.append(str(lst[i]) + c)
        s.append(str(lst[8]))# 9
        x = ''.join(s).replace(' ' , '')
        if eval(x) == 100:
            print(x)
    
if __name__ == '__main__':
    one_hundred()