LeetCode Top Interview 150
34. Find First and Last Position of Element in Sorted Array
Medium
Given an array of integers nums sorted in non-decreasing order, find the starting and ending position of a given target value.
If target is not found in the array, return [-1, -1].
You must write an algorithm with O(log n) runtime complexity.
Example 1:
Input: nums = [5,7,7,8,8,10], target = 8
Output: [3,4]
Example 2:
Input: nums = [5,7,7,8,8,10], target = 6
Output: [-1,-1]
Example 3:
Input: nums = [], target = 0
Output: [-1,-1]
Constraints:
0 <= nums.length <= 105-109 <= nums[i] <= 109numsis a non-decreasing array.-109 <= target <= 109
Solution
func searchRange(nums []int, target int) []int {
ans := make([]int, 2)
ans[0] = helper(nums, target, false)
ans[1] = helper(nums, target, true)
return ans
}
func helper(nums []int, target int, equals bool) int {
l, r := 0, len(nums)-1
result := -1
for l <= r {
mid := l + (r-l)/2
if nums[mid] == target {
result = mid
}
if nums[mid] < target || (nums[mid] == target && equals) {
l = mid + 1
} else {
r = mid - 1
}
}
return result
}