# 702. Search in a Sorted Array of Unknown Size

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]`.

``````// Forward declaration of ArrayReader class.

class Solution {
public:
int left = 0, right = INT_MAX;
while (left < right) {
int mid = left + (right - left) / 2, x = reader.get(mid);
if (x == target) return mid;
else if (x < target) left = mid + 1;
else right = mid;
}
return -1;
}
};
``````

Binary Search

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

https://leetcode.com/problems/search-in-a-sorted-array-of-unknown-size/discuss/171669/Straight-forward-binary-search.

https://leetcode.com/problems/search-in-a-sorted-array-of-unknown-size/discuss/151685/Shortest-and-cleanest-Java-solution-so-far...

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