Write code in c$++$

Given an array of integers$$nums$$which is sorted in ascending order, and an integer$$target$,$ write a function to search$$target$$in$$nums$.$ If$$target$$exists$,$ then return its index. Otherwise, return$-1.$

You must write an algorithm with$$O$($log n$)$runtime complexity.

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Example $1$:

Input: nums $=[-1,0,3,5,9,12],$ target $=9$

Output: $4$

Explanation: $9$ exists in nums and its index is $4$

Example $2$:

Input: nums $=[-1,0,3,5,9,12],$ target $=2$

Output: $-1$

Explanation: $2$ does not exist in nums so return $-1$

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Constraints:

$1<=$ nums.length $<=104$

$-104<$ nums$[$i$],$ target $<104$

All the integers in$$nums$$are$$unique$.$

nums$$is sorted in ascending order.