leetcode解题方案--034--Search for a Range

题目

分析

查找给定数在数组的范围，数组已排序。
思路是 二分法查找所求范围的最左侧和最右侧，分别输出即可。
注意的是，得到左指针和右指针需要分别判定两种边界条件。
一个是左序号为0或右序号是数组最后一个，另一个是不存在返回-1

class Solution {        public static int[] searchRange(int[] nums, int target) {        if (nums == null || nums.length <= 0) {            return new int[]{-1, -1};        }        int leftlow = 0;        int lefthigh = nums.length - 1;        int left = 0;        while (lefthigh - leftlow > 1) {            int mid = (lefthigh + leftlow) / 2;            if (nums[mid] >= target) {                lefthigh = mid;            } else {                leftlow = mid;            }        }        int rightlow = 0;        int righthigh = nums.length - 1;        int right = 0;        while (righthigh - rightlow > 1) {            int mid = (righthigh + rightlow) / 2;            if (nums[mid] <= target) {                rightlow = mid;            } else {                righthigh = mid;            }        }        if (nums[leftlow]!=target && nums[lefthigh]!=target) {            return new int[]{-1,-1};        }        left = nums[leftlow] == target ? leftlow : lefthigh;        right = nums[righthigh] == target ? righthigh : rightlow;        return new int[]{left, right};    }}