problem.py

def solutionC(a):
    g = {}
    maxnum = 1
    for i in range(0, len(a)):
        if a[i] > 0:
            g[a[i]] = 1
            maxnum = max(maxnum, a[i])
    for j in range(1, maxnum+2):
        if j not in g:
            return j
    return 1

def solutionD(a):
    positive = filter(lambda x: x >= 0, a)
    positive.sort()
    if len(positive) == 0:
        return 1
    prev = positive[0]
    for i in range(1, len(positive)):
        if (prev+1) < positive[i]:
            return prev+1
        else:
            prev = positive[i]
    return prev+1