NumberOfDiscIntersec tions https app codility com programmers lessons

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"""
NumberOfDiscIntersections
https://app.codility.com/programmers/lessons/6-sorting/number_of_disc_intersections/
"""
def solution(A):
limit = 10000000
code_out_of_limit = -1
len_A = len(A)
mid_opening_counts = [0 for _ in A]
mid_closing_counts = [0 for _ in A]
currently_seen_disc_count = 0
total_intersections = 0
for i, x in enumerate(A):
if i - x >= 0:
mid_opening_counts[i-x] += 1
else:
total_intersections += currently_seen_disc_count
currently_seen_disc_count += 1
if i + x < len_A:
mid_closing_counts[i+x] += 1
for i, mid_opening_counts_i in enumerate(mid_opening_counts):
total_intersections += currently_seen_disc_count * mid_opening_counts_i
total_intersections += mid_opening_counts_i*(mid_opening_counts_i - 1)//2
currently_seen_disc_count += mid_opening_counts_i
currently_seen_disc_count -= mid_closing_counts[i]
if total_intersections > limit:
return code_out_of_limit
return total_intersections
if __name__ == "__main__":
for arr, expected in [
([0,0,0], 0),
([1,2,3], 3),
([1,5,2,1,4,0], 11),
([3,2,1,3], 6)
]:
solved = solution(arr)
assert expected == solved, (expected, solved)