81. Search in Rotated Sorted Array II.md

81. Search in Rotated Sorted Array II

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leetcode Daily Challenge on November 20th, 2020.

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Difficulty : Medium

Related Topics : Array、BinarySearch

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Suppose an array sorted in ascending order is rotated at some pivot unknown to you beforehand.

(i.e., [0,0,1,2,2,5,6] might become [2,5,6,0,0,1,2]).

You are given a target value to search. If found in the array return true, otherwise return false.

Example 1:

Input: nums = [2,5,6,0,0,1,2], target = 0
Output: true

Example 2:

Input: nums = [2,5,6,0,0,1,2], target = 3
Output: false

Follow up:

• This is a follow up problem to Search in Rotated Sorted Array, where nums may contain duplicates.
• Would this affect the run-time complexity? How and why?

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Solution

• mine
  • Java
    • ``

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• the most votes
  • Runtime: 0 ms, faster than 100.00%, Memory Usage: 38.9 MB, less than 38.27% of Java online submissions

    public boolean search(int[] nums, int target) {
        if (nums == null || nums.length == 0) return false;
    
        int start = 0;
        int end = nums.length - 1;
        while (start <= end) {
            int mid = (start + end) >>> 1;
            if (nums[mid] == target) return true;
    
            if (nums[start] == nums[mid]) {
                start++;
                continue;
            }
            //first part is orderly
            if (nums[start] < nums[mid]) {
                if (nums[mid] > target && nums[start] <= target) {
                    //target in the first part
                    end = mid - 1;
                } else {
                    start = mid + 1;
                }
            } else {
                //last part is orderly
                if (nums[mid] < target && nums[end] >= target) {
                    //target in the end part
                    start = mid + 1;
                } else {
                    end = mid - 1;
                }
            }
        }
        return false;
    }
    

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