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]。
进阶:
你可以设计并实现时间复杂度为 O(log n) 的算法解决此问题吗?
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]
class Solution {
public int[] searchRange(int[] nums, int target) {
if (nums == null || nums.length == 0) {
return new int[]{-1, -1};
}
int left = findLeft(nums, 0, nums.length - 1, target);
if (nums[left] != target) return new int[]{-1, -1};
int right = findRight(nums, left, nums.length - 1, target);
return new int[]{left, right};
}
int findLeft(int[] nums, int left, int right, int target) {
while (left < right) {
int mid = (left + right) >> 1;
if (nums[mid] >= target) {
right = mid;
} else {
left = mid + 1;
}
}
return left;
}
int findRight(int[] nums, int left, int right, int target) {
while (left < right) {
int mid = (left + right + 1) >> 1;
if (nums[mid] <= target) {
left = mid;
} else {
right = mid - 1;
}
}
return left;
}
}
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