34. Search for a Range

找到的答案，二分查找法的改良版

public int[] searchRange(int[] A, int target) {int start = Solution.firstGreaterEqual(A, target);if (start == A.length || A[start] != target) {return new int[]{-1, -1};}return new int[]{start, Solution.firstGreaterEqual(A, target + 1) - 1};}//找到大于或等于目标的第一个数。//如果目标是大于A[A.length-1] 返回A.length。//其实这是在C++ STL lower_bound相同。private static int firstGreaterEqual(int[] A, int target) {int low = 0, high = A.length;while (low < high) {int mid = low + (high - low)/2;//low <= mid < highif (A[mid] < target) {low = mid + 1;} else {//should not be mid-1 when A[mid]==target.//could be mid even if A[mid]>target because mid<high.high = mid;}}return low;}