Description
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] <= 109nums is a non-decreasing array.-109 <= target <= 109
Solutions
Solution 1: Binary Search
We can perform two binary searches to find the left boundary and the right boundary.
The time complexity is O(log n), where n is the length of the array nums. The space complexity is O(1).
PythonJavaC++GoTypeScriptRustJavaScriptC#PHPKotlin
class Solution:
def searchRange(self, nums: List[int], target: int) -> List[int]:
l = bisect_left(nums, target)
r = bisect_left(nums, target + 1)
return [-1, -1] if l == r else [l, r - 1](code-box)
class Solution {
public int[] searchRange(int[] nums, int target) {
int l = search(nums, target);
int r = search(nums, target + 1);
return l == r ? new int[] {-1, -1} : new int[] {l, r - 1};
}
private int search(int[] nums, int x) {
int left = 0, right = nums.length;
while (left < right) {
int mid = (left + right) >>> 1;
if (nums[mid] >= x) {
right = mid;
} else {
left = mid + 1;
}
}
return left;
}
}(code-box)
class Solution {
public:
vector<int> searchRange(vector<int>& nums, int target) {
int l = lower_bound(nums.begin(), nums.end(), target) - nums.begin();
int r = lower_bound(nums.begin(), nums.end(), target + 1) - nums.begin();
if (l == r) {
return {-1, -1};
}
return {l, r - 1};
}
};(code-box)
func searchRange(nums []int, target int) []int {
l := sort.SearchInts(nums, target)
r := sort.SearchInts(nums, target+1)
if l == r {
return []int{-1, -1}
}
return []int{l, r - 1}
}(code-box)
function searchRange(nums: number[], target: number): number[] {
const search = (x: number): number => {
let [left, right] = [0, nums.length];
while (left < right) {
const mid = (left + right) >> 1;
if (nums[mid] >= x) {
right = mid;
} else {
left = mid + 1;
}
}
return left;
};
const l = search(target);
const r = search(target + 1);
return l === r ? [-1, -1] : [l, r - 1];
}(code-box)
impl Solution {
pub fn search_range(nums: Vec<i32>, target: i32) -> Vec<i32> {
let n = nums.len();
let search = |x| {
let mut left = 0;
let mut right = n;
while left < right {
let mid = left + (right - left) / 2;
if nums[mid] < x {
left = mid + 1;
} else {
right = mid;
}
}
left
};
let l = search(target);
let r = search(target + 1);
if l == r {
return vec![-1, -1];
}
vec![l as i32, (r - 1) as i32]
}
}(code-box)
/**
* @param {number[]} nums
* @param {number} target
* @return {number[]}
*/
var searchRange = function (nums, target) {
function search(x) {
let left = 0,
right = nums.length;
while (left < right) {
const mid = (left + right) >> 1;
if (nums[mid] >= x) {
right = mid;
} else {
left = mid + 1;
}
}
return left;
}
const l = search(target);
const r = search(target + 1);
return l == r ? [-1, -1] : [l, r - 1];
};(code-box)
public class Solution {
public int[] SearchRange(int[] nums, int target) {
int l = Search(nums, target);
int r = Search(nums, target + 1);
return l == r ? new int[] {-1, -1} : new int[] {l, r - 1};
}
private int Search(int[] nums, int x) {
int left = 0, right = nums.Length;
while (left < right) {
int mid = (left + right) >>> 1;
if (nums[mid] >= x) {
right = mid;
} else {
left = mid + 1;
}
}
return left;
}
}(code-box)
class Solution {
/**
* @param Integer[] $nums
* @param Integer $target
* @return Integer[]
*/
function searchRange($nums, $target) {
$search = function ($x) use ($nums) {
$left = 0;
$right = count($nums);
while ($left < $right) {
$mid = intdiv($left + $right, 2);
if ($nums[$mid] >= $x) {
$right = $mid;
} else {
$left = $mid + 1;
}
}
return $left;
};
$l = $search($target);
$r = $search($target + 1);
return $l === $r ? [-1, -1] : [$l, $r - 1];
}
}(code-box)
class Solution {
fun searchRange(nums: IntArray, target: Int): IntArray {
val left = this.search(nums, target)
val right = this.search(nums, target + 1)
return if (left == right) intArrayOf(-1, -1) else intArrayOf(left, right - 1)
}
private fun search(nums: IntArray, target: Int): Int {
var left = 0
var right = nums.size
while (left < right) {
val middle = (left + right) / 2
if (nums[middle] < target) {
left = middle + 1
} else {
right = middle
}
}
return left
}
}(code-box)
