06_codility_missing.py

def solution(A):
    d = {}
    result = 0
    for i in range(len(A)):
        if A[i] not in d and A[i] >= 1:
            d[A[i]] = 0  
    j = 1
    while j <= 100010:
        if not j in d:
            result = j
            break
        j += 1
        
    return result
    
#https://codility.com/demo/results/demoMC99B7-2H5/