leetcode1064

思路1:使用顺序查找

class Solution:
    def fixedPoint(self, A: 'List[int]') -> int:
        for i in range(len(A)):
            if i == A[i]:
                return i
        return -1

思路2:使用二分查找

class Solution:
    def fixedPoint(self, A: 'List[int]') -> int:
        n = len(A)
        i = 0
        j = n - 1
        while i <=j:
            mid = i + (j - i) // 2
            if A[mid] == mid:
                return mid
            elif A[mid] < mid:
                i = mid + 1
            else:
                j = mid - 1
        return -1