[LeetCode Hot 100] LeetCode33. 搜索旋转排序数组

题目描述

思路

• 如果nums[left] <= nums[mid]，则[left, mid]有序
• 如果nums[left] > nums[mid]，则[mid，right]有序

方法一：

class Solution {
    public int search(int[] nums, int target) {
        if (nums == null || nums.length == 0) return -1;
        int left = 0, right = nums.length - 1;
        while (left <= right) {
            int mid = left + (right - left) / 2;
            if (target == nums[mid]) return mid;
            if (nums[left] <= nums[mid]) {  // 左边有序
                if (target >= nums[left] && target < nums[mid]) { // target在左边
                    right = mid - 1;
                } else { // target在右边
                    left = mid + 1;
                }
            } else {  // 右边有序
                if (target > nums[mid] && target <= nums[right]) { // target在右边
                    left = mid + 1;
                } else {
                    right = mid - 1;
                }
            }
        }
        return -1;
    }
}