力扣，https://leetcode.cn/problems/zai-pai-xu-shu-zu-zhong-cha-zhao-shu-zi-lcof/description/
二分查找，边界问题
solution1
自己的方法，其实不太好
class Solution {public int countTarget(int[] scores, int target) {if (scores.length == 0) {return 0;}int[] inxArray = new int[]{-1, -1};binarySearch(0, scores.length - 1, scores, target, inxArray);if (inxArray[0] == -1 && inxArray[1] == -1) {return 0;}return inxArray[1] - inxArray[0] + 1;}public void binarySearch(int start, int end, int[] scores, int target, int[] inxArray) {if (start > end) {return;}int mid = start + (end - start) / 2;if (scores[mid] == target) {inxArray[0] = mid;inxArray[1] = mid;while (inxArray[0] - 1 >= 0 && scores[inxArray[0] - 1] == target) {inxArray[0] -= 1;}while (inxArray[1] + 1 < scores.length && scores[inxArray[1] + 1] == target) {inxArray[1] += 1;}return;} else if (scores[mid] < target) {start = mid + 1;binarySearch(start, end, scores, target, inxArray);} else {end = mid - 1;binarySearch(start, end, scores, target, inxArray);}}}
