# Leetcode 704 - Binary Search

`Note:`

- To find the
`target`

but not`first element bigger than or equal to target`

, or`last element smaller than or equal to target`

, use`<=`

, and we don’t need a last check on`nums[left]`

with`target`

. - Don’t need
`add 1`

to`left + right >> 1`

because there won’t be infinite loops, and we won’t miss any ans.

`Question:`

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.

`Example:`

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

`Code:`

1 | /** |