摘要：首先，建立二元結(jié)果數(shù)組，起點(diǎn)，終點(diǎn)。二分法求左邊界當(dāng)中點(diǎn)小于，移向中點(diǎn)，否則移向中點(diǎn)先判斷起點(diǎn)，再判斷終點(diǎn)是否等于，如果是，賦值給。

Given a sorted array of n integers, find the starting and ending position of a given target value.

If the target is not found in the array, return [-1, -1].

Given [5, 7, 7, 8, 8, 10] and target value 8,
return [3, 4].

O(log n) time.

首先，建立二元結(jié)果數(shù)組res，起點(diǎn)start，終點(diǎn)end。
二分法求左邊界：
當(dāng)中點(diǎn)小于target，start移向中點(diǎn)，否則end移向中點(diǎn)；
先判斷起點(diǎn)，再判斷終點(diǎn)是否等于target，如果是，賦值給res[0]。
二分法求右邊界：
當(dāng)中點(diǎn)大于target，end移向中點(diǎn)，否則start移向中點(diǎn)；
先判斷終點(diǎn)，再判斷起點(diǎn)是否等于target，如果是，賦值給res[1]。
返回res。

public class Solution {
    public int[] searchRange(int[] A, int target) {
        int []res = {-1, -1};
        if (A == null || A.length == 0) return res;
        int start = 0, end = A.length - 1;
        int mid;
        while (start + 1 < end) {
            mid = start + (end - start) / 2;
            if (A[mid] < target) start = mid;
            else end = mid;
        }
        if (A[start] == target) res[0] = start;
        else if (A[end] == target) res[0] = end;
        else return res;
        start = 0;
        end = A.length - 1;
        while (start + 1 < end) {
            mid = start + (end - start) / 2;
            if (A[mid] > target) end = mid;
            else start = mid;
        }
        if (A[end] == target) res[1] = end;
        else if (A[start] == target) res[1] = start;
        else return res;
        return res;
    }
}

public class Solution {
    public int[] searchRange(int[] nums, int target) {
        int n = nums.length;
        int[] res = {-1, -1};
        int start = 0, end = n-1;
        while (nums[start] < nums[end]) {
            int mid = start + (end - start) / 2;
            if (nums[mid] > target) end = mid - 1;
            else if (nums[mid] < target) start = mid + 1;
            else {
                if (nums[start] < target) start++;
                if (nums[end] > target) end--;
            }
        }
        if (nums[start] == target) {
            res[0] = start;
            res[1] = end;
        }
        return res;
    }
}