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| 1 | +/* |
| 2 | + * @lc app=leetcode.cn id=34 lang=java |
| 3 | + * |
| 4 | + * [34] 在排序数组中查找元素的第一个和最后一个位置 |
| 5 | + * |
| 6 | + * https://leetcode-cn.com/problems/find-first-and-last-position-of-element-in-sorted-array/description/ |
| 7 | + * |
| 8 | + * algorithms |
| 9 | + * Medium (39.56%) |
| 10 | + * Likes: 490 |
| 11 | + * Dislikes: 0 |
| 12 | + * Total Accepted: 105.8K |
| 13 | + * Total Submissions: 265.6K |
| 14 | + * Testcase Example: '[5,7,7,8,8,10]\n8' |
| 15 | + * |
| 16 | + * 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。 |
| 17 | + * |
| 18 | + * 你的算法时间复杂度必须是 O(log n) 级别。 |
| 19 | + * |
| 20 | + * 如果数组中不存在目标值,返回 [-1, -1]。 |
| 21 | + * |
| 22 | + * 示例 1: |
| 23 | + * |
| 24 | + * 输入: nums = [5,7,7,8,8,10], target = 8 |
| 25 | + * 输出: [3,4] |
| 26 | + * |
| 27 | + * 示例 2: |
| 28 | + * |
| 29 | + * 输入: nums = [5,7,7,8,8,10], target = 6 |
| 30 | + * 输出: [-1,-1] |
| 31 | + * |
| 32 | + */ |
| 33 | + |
| 34 | +// @lc code=start |
| 35 | +class Solution { |
| 36 | + public int[] searchRange(int[] nums, int target) { |
| 37 | + int left = searchLeft(nums, target, 0, nums.length - 1); |
| 38 | + if (left >= nums.length || nums[left] != target) { |
| 39 | + return new int[] {-1, -1}; |
| 40 | + } |
| 41 | + |
| 42 | + int right = searchRight(nums, target, left, nums.length - 1); |
| 43 | + return new int[] {left, right}; |
| 44 | + } |
| 45 | + |
| 46 | + public int searchLeft(int[] nums, int target, int start, int end) { |
| 47 | + int left = start; |
| 48 | + int right = end; |
| 49 | + |
| 50 | + while (left <= right) { |
| 51 | + int mid = left + (right - left) / 2; |
| 52 | + if (nums[mid] < target) { |
| 53 | + left = mid + 1; |
| 54 | + } else if (nums[mid] > target) { |
| 55 | + right = mid - 1; |
| 56 | + } else if (nums[mid] == target) { |
| 57 | + right = mid - 1; |
| 58 | + } |
| 59 | + } |
| 60 | + |
| 61 | + return left; |
| 62 | + } |
| 63 | + |
| 64 | + public int searchRight(int[] nums, int target, int start, int end) { |
| 65 | + int left = start; |
| 66 | + int right = end; |
| 67 | + |
| 68 | + while (left <= right) { |
| 69 | + int mid = left + (right - left) / 2; |
| 70 | + if (nums[mid] < target) { |
| 71 | + left = mid + 1; |
| 72 | + } else if (nums[mid] > target) { |
| 73 | + right = mid - 1; |
| 74 | + } else if (nums[mid] == target) { |
| 75 | + left = mid + 1; |
| 76 | + } |
| 77 | + } |
| 78 | + |
| 79 | + return right; |
| 80 | + } |
| 81 | +} |
| 82 | +// @lc code=end |
| 83 | + |
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