704. Binary Search #

Problem #

Given a sorted (in ascending order) integer array nums of n elements and a target value, write a function to search target in nums. If target exists, then return its index, otherwise return -1.

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

Note:

1. You may assume that all elements in nums are unique.
2. n will be in the range [1, 10000].
3. The value of each element in nums will be in the range [-9999, 9999].

Problem Summary #

Given an ordered (ascending) integer array nums with n elements and a target value target, write a function to search for target in nums. If the target value exists, return its index; otherwise, return -1.

Notes:

• You may assume that all elements in nums are unique.
• n will be in the range [1, 10000].
• Each element of nums will be in the range [-9999, 9999].

Solution Approach #

• Given an array, search for the index of the element equal to target in the array. If found, output the index; if not found, output -1.
• Easy problem, a straightforward binary search problem.

Code #

package leetcode

func search704(nums []int, target int) int {
	low, high := 0, len(nums)-1
	for low <= high {
		mid := low + (high-low)>>1
		if nums[mid] == target {
			return mid
		} else if nums[mid] > target {
			high = mid - 1
		} else {
			low = mid + 1
		}
	}
	return -1
}