反數列使用 binary search

test.py

import bisect
from typing import List


def reversePairs(nums: List[int]) -> int:
    q = []
    res = 0
    for v in nums:
        i = bisect.bisect_left(q, -v)
        res += i
        q[i:i] = [-v]
    return res


if __name__ == '__main__':
    data = [1, 2, 3, 5, 4]
    print(reversePairs(data))

    data = [1, 5, 3, 2, 4]
    print(reversePairs(data))

    data = [1, 4, 3, 2, 5]
    print(reversePairs(data))