33. Search in Rotated Sorted Array

package com.lingyejun.dating.chap11.toutiao;

public class RotatedArrayQuery {


    /**
     * 33. Search in Rotated Sorted Array
     * 查找目标值下标
     *
     * @param nums
     * @param target
     * @return
     */
    public int searchTargetIndex(int[] nums, int target) {
        int start = 0;
        int end = nums.length - 1;

        while (start <= end) {

            // (start ... middle ... end)
            int mid = (start + end) / 2;

            if (nums[mid] == target) {
                return mid;
            }

            // 前半段数组是有序的
            if (nums[start] < nums[mid]) {
                // target在前半段数组中
                if (target < nums[mid] && target >= nums[start]) {
                    // 将原数组折半，取出前半段数组
                    end = mid - 1;
                } else {
                    // target在后半段数组中
                    start = mid + 1;
                }
            }

            // 后半段数组是有序的
            else if (nums[mid] < nums[end]) {
                // target在后半段数组中
                if (target > nums[mid] && target <= nums[end]) {
                    // 将原数组折半，取出后半段数组
                    start = mid + 1;
                } else {
                    // target在前半段数组中
                    end = mid - 1;
                }
            } else {
                // 此种场景{1, 0, 1, 1, 1} start = mid = end
                start++;
            }
        }
        return -1;
    }

    /**
     * 81. Search in Rotated Sorted Array II
     *
     * 查找是否存在目标值
     *
     * @param nums
     * @param target
     * @return
     */
    public static boolean searchExistsKey(int nums[], int target) {
        int start = 0;
        int end = nums.length - 1;

        while (start <= end) {

            int mid = (start + end) / 2;

            if (nums[mid] == target) {
                return true;
            }

            if (nums[start] < nums[mid]) {

                if (nums[start] <= target && target < nums[mid]) {
                    end = mid - 1;
                } else {
                    start = mid + 1;
                }
            } else if (nums[start] > nums[mid]) {
                if (nums[mid] < target && target <= nums[end]) {
                    start = mid + 1;
                } else {
                    end = mid - 1;
                }

            } else {
                start++;
            }
        }
        return false;
    }

    public static void main(String[] args) {

        int[] array = new int[]{1, 0, 1, 1, 1};

        RotatedArrayQuery caq = new RotatedArrayQuery();

        System.out.println(caq.searchTargetIndex(array, 0));
        System.out.println(caq.searchExistsKey(array, 1));
    }

}