LeetCode-in-Java
540. Single Element in a Sorted Array
Medium
You are given a sorted array consisting of only integers where every element appears exactly twice, except for one element which appears exactly once.
Return the single element that appears only once.
Your solution must run in O(log n) time and O(1) space.
Example 1:
Input: nums = [1,1,2,3,3,4,4,8,8]
Output: 2
Example 2:
Input: nums = [3,3,7,7,10,11,11]
Output: 10
Constraints:
1 <= nums.length <= 1050 <= nums[i] <= 105
Solution
public class Solution {
public int singleNonDuplicate(int[] nums) {
int start = 0;
int end = nums.length - 1;
while (start < end) {
int mid = start + (end - start) / 2;
if (mid + 1 < nums.length
&& nums[mid] != nums[mid + 1]
&& mid - 1 >= 0
&& nums[mid] != nums[mid - 1]) {
return nums[mid];
} else if (mid + 1 < nums.length && nums[mid] == nums[mid + 1] && mid % 2 == 0) {
start = mid + 1;
} else if (mid - 1 >= 0 && nums[mid] == nums[mid - 1] && mid % 2 == 1) {
start = mid + 1;
} else {
end = mid - 1;
}
}
return nums[start];
}
}