Codility MissingInteger

int solution(int A[], int N) {
    // write your code in C99
    int minimal = 1;
    int i = 0;
    int * array = calloc(N + 1, sizeof(int));
    
    for (; i < N; i++) {
     
        if (A[i] > 0 && A[i] <= N && array[A[i]] == 0) {
            array[A[i]] = 1;
            
        }
        
    }
    
    for (i = 0; i < N; i++) {
        if (array[i+1] == 0) {
            
            free(array);
            return i + 1;   
        }
    }
    
    free(array);
    return N + 1;
}