704. Binary Search

Easy
​
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
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
Constraints:
  • 1 <= nums.length <= 104
  • -104 < nums[i], target < 104
  • All the integers in nums are unique.
  • nums is sorted in ascending order.

解題

Binary search
func search(nums []int, target int) int {
left := 0
right := len(nums)-1
​
for left <= right {
mid := ( left + right )/2
​
if nums[mid] == target { return mid }
​
if nums[mid] > target {
right = mid - 1
} else {
left = mid + 1
}
}
​
return -1
}