[Python] 4.1. FrogRiverOne

https://app.codility.com/programmers/lessons/4-counting_elements/

4. Counting Elements lesson - Learn to Code - Codility

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정답률: 100%
시간복잡도: O(N)

def solution(X, A):

    check = [1] + [0] * X
    cnt = 0
    for K in range(len(A)):
        if check[A[K]] == 0:
            check[A[K]] = 1
            cnt += 1
        if cnt == X:
            return K

    if cnt != X:
        return -1