# 702-search-in-a-sorted-array-of-unknown-size

## Question

https://leetcode.com/problems/search-in-a-sorted-array-of-unknown-size/description/

Given an integer array sorted in ascending order, write a function to search`target`in`nums`. If`target`exists, then return its index, otherwise return`-1`.However, the array size is unknown to you. You may only access the array using an`ArrayReader` interface, where `ArrayReader.get(k)`returns the element of the array at index`k` (0-indexed).

You may assume all integers in the array are less than `10000`, and if you access the array out of bounds,`ArrayReader.get`will return`2147483647`.

Example 1:

``````Input: array = [-1,0,3,5,9,12], target = 9
Output: 4
Explanation: 9 exists in nums and its index is 4
``````

Example 2:

``````Input: array = [-1,0,3,5,9,12], target = 2
Output: -1
Explanation: 2 does not exist in nums so return -1
``````

Note:

1. You may assume that all elements in the array are unique.
2. The value of each element in the array will be in the range [-9999, 9999].

## Thought Process

1. Binary Search
1. We set our search index to be from 0 to 2147483647, named lo and hi
2. Our search ends when we hit our target or hi > lo
3. Time complexity O(1) from 32 times or search
4. Space complexity O(1)

## Solution

``````class Solution {
int lo = 0, hi = Integer.MAX_VALUE;
while (lo <= hi) {
int mi = lo + (hi - lo) / 2;
if (val == target) return mi;
else if (val < target) lo = mi + 1;
else hi = mi - 1;
}
return -1;
}
}
``````