1898. 可移除字符的最大数目

class Solution:
    def maximumRemovals(self, s: str, p: str, removable: List[int]) -> int:
        def search_II(check):
            left = 1
            right = len(removable)
            while left<=right:
                mid = (left+right)>>1
                if check(mid):
                    left = mid+1
                else:
                    right = mid-1
            return right 
        def check(x) ->bool:
            # 注意，python的str是不可变的，转list去计算可以，但是会超时，所以建一个辅助list。
            sn = len(s)
            pn = len(p)
            state = [True]*sn
            for i in range(x):
                state[removable[i]] = False
            ans = 0
            i,j = 0,0
            while i<sn and j<pn:
                if state[i] and s[i]==p[j]:
                    i += 1
                    j += 1
                    ans += 1
                else:
                    i += 1
            return ans == pn

        return search_II(check)