go代码

func getMissingNumber(nums []int) int {

    if len(nums) == 0 || len(nums) == 1 || 
            nums[len(nums) - 1] == len(nums) - 1{
        return len(nums)
    }
    if nums[0] !=0 {
        return 0
    }
    start,end :=0,len(nums)-1
    for ;end - start > 1 ; {
        mid := (start + end) >> 1
        if nums[mid] <= mid {
            start = mid
        }else {
            end = mid
        }

    }
    return nums[end]-1

}