题目描述

参考：
https://blog.csdn.net/WJPnb1/article/details/126360962?spm=1001.2014.3001.5502

寻找第一个大于等于x的，即最后时刻l1及左边都小于x，r1及右边都大于x。
更新时，nums[mid]小于x时
将l1 更新为mid–>nums[l1]<mid满足上述要求

 while l1+1!=r1:
            mid = (l1+r1)//2
            if nums[mid]<x:
                l1 = mid
            else:
                r1 = mid

寻找最后一个大于等于x的，最后时刻l2及左边都小于等于x,r2及右边都大于x。
更新时，当nums[mid]>x时，将r2更新为mid,即是使nums[r2]>x

   while l2+1!=r2:
            mid = (l2+r2)//2
            if nums[mid]>x:
                r2 = mid
            else:
                l2 = mid

Python代码

N = 100010

nums = [0 for _ in range(N)]

if __name__ == '__main__':
    n,q = map(int,input().split())

    nums[:n] = list(map(int,input().split()))

    for i in range(q):
        x = int(input())

        l1,r1 = -1,n
        l2,r2 = -1,n 

        while l1+1!=r1:
            mid = (l1+r1)//2
            if nums[mid]<x:
                l1 = mid
            else:
                r1 = mid

        if nums[r1] != x:
            print(-1,-1)
            continue

        while l2+1!=r2:
            mid = (l2+r2)//2
            if nums[mid]>x:
                r2 = mid
            else:
                l2 = mid

        if nums[l2] == x:
            print(r1,l2)
        else:
            print(r1,r2)