HackerEarth The exam problem solution

In this HackerEarth The exam problem solution Kate is wizard. Now she should pass the exam.

During the exam she have to go into the magic room N times. Initially there are X magic items in the room. Before each visit she can use magic to decrease the number of magic items in the room. For each item she spends 1 mana point to destroy it. After each visit the number of magic items increases by 2 times. She can't go into room if there are more than L magic items in it. What minimum mana points does Kate need to pass the exam?

You need to solve this problem for several test cases.

HackerEarth The exam problem solution.

def solve():
    x, l, n = map(int, input().split())

    min_erased = -1
    max_erased = x
    while max_erased - min_erased > 1:
        erased = (min_erased + max_erased) // 2

        cur_x = x - erased
        good = True
        for it in range(n):
            if cur_x > l:
                good = False
                break
            cur_x *= 2

        if good:
            max_erased = erased
        else:
            min_erased = erased

    print(max_erased)


def main():
    t = int(input())
    for i in range(t):
        solve()


main()