题目:
给定一个按照升序排列的整数数组 nums，和一个目标值 target。找出给定目标值在数组中的开始位置和结束位置。
如果数组中不存在目标值 target，返回 [-1, -1]。
示例 1：
- 输入：nums = [5,7,7,8,8,10], target = 8
- 输出：[3,4]
示例 2：
- 输入：nums = [5,7,7,8,8,10], target = 6
- 输出：[-1,-1]
示例 3：
- 输入：nums = [], target = 0
- 输出：[-1,-1]
java:
public class Leetcode034 {
public static int[] searchRange(int[] nums, int target) {
int leftBorder = getLeftBorder(nums, target);
int rightBorder = getRightBorder(nums, target);
if (leftBorder == -2 && rightBorder == -2) return new int[]{-1, -1};
if (rightBorder - leftBorder > 1) return new int[]{leftBorder + 1, rightBorder - 1};
return new int[]{-1, -1};
}
private static int getRightBorder(int[] nums, int target) {
int left = 0;
int right = nums.length - 1;
int rightBorder = -2;
while (left <= right) {
int middle = left + (right - left) / 2;
if (nums[middle] > target) {
right = middle - 1;
} else {
left = middle + 1;
rightBorder = left;
}
}
return rightBorder;
}
private static int getLeftBorder(int[] nums, int target) {
int left = 0;
int right = nums.length - 1;
int leftBorder = -2;
while (left <= right) {
int middle = left + (right - left) / 2;
if (nums[middle] >= target) {
right = middle - 1;
leftBorder = right;
} else {
left = middle + 1;
}
}
return leftBorder;
}
public static void main(String[] args) {
int[] nums = {5, 7, 7,8, 10};
int[] ints = searchRange(nums, 8);
for (int i = 0; i < ints.length; i++) {
System.out.println(ints[i]);
}
}
}
Go:
package LeetCode
func SearchRange(nums []int, target int) []int {
left := getLeft(nums, target)
right := getRight(nums, target)
if left == -2 || right == -2 {
return []int{-1, -1}
}
if right-left > 1 {
return []int{left + 1, right - 1}
}
return []int{-1, -1}
}
func getRight(nums []int, target int) int {
left, right := 0, len(nums)-1
rightBorder := -2
for left <= right {
mid := left + ((right - left) >> 1)
if nums[mid] > target {
//找到第一个大于target的位置.
right = mid - 1
} else {
left = mid + 1
rightBorder = left
}
}
return rightBorder
}
func getLeft(nums []int, target int) int {
left, right := 0, len(nums)-1
leftBorder := -2
for left <= right {
middle := left + ((right - left) >> 1)
if nums[middle] >= target {
//找到第一个等于target的位置.
right = middle - 1
leftBorder = right
} else {
left = middle + 1
}
}
return leftBorder
}
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