必会算法：在旋转有序的数组中搜索

 /**
     * 暴力破解法
     *
     * @param num    给定的旋转后数组
     * @param target 目标值
     * @return 查询结果
     */
    public static int getIndex(int[] num, int target) {
        if (num == null || num.length == 0) {
            return -1;
        }
        for (int i = 0; i < num.length; i++) {
            if (num[i] == target) {
                return i;
            }
        }
        return -1;
    }

public static int getIndex(int[] num, int target) {
   if (num == null || num.length == 0) {
       return -1;
   }
   int start = 0;
   int end = num.length - 1;
   int mid;
   while (start + 1 < end) {
        mid = start + (end - start) / 2;
       if (num[mid] == target) {
           return mid;
       }
       if (num[mid] > num[start]) {
           if (target <= num[mid] && num[start] <= target) {
                end = mid;
           } else {
                start = mid;
           }
       } else {
           if (target >= num[mid] && target <= num[end]) {
                start = mid;
           } else {

                end = mid;
           }
       }
   }
   if (num[start] == target) {
       return start;
   }
   if (num[end] == target) {
       return end;
   }
   return -1;
}