题解 | #缺失数字#

#
# 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
#
# 找缺失数字
# @param a int整型一维数组 给定的数字串
# @return int整型
#
class Solution:
    def solve(self , a ):
        # write code here
        start = 0
        end = len(a) - 1
        middle = (start + end)//2
        while (end - start) > 1:
            if a[middle] > (a[0] + middle):
                end = middle
            else:
                start = middle
            middle = (start + end)//2
        if((a[end] == (a[0]+end)) & (a[0]!=0)):
            return a[0] - 1
        elif((a[end] == (a[0]+end)) & (a[0]==0)):
            return a[end] + 1
        return a[end] -1