Problem:
You are given a sorted array consisting of only integers where every element appears exactly twice, except for one element which appears exactly once. Find this single element that appears only once.
Example 1:
Input: [1,1,2,3,3,4,4,8,8]
Output: 2
Example 2:
Input: [3,3,7,7,10,11,11]
Output: 10
Note: Your solution should run in O(log n) time and O(1) space.
思路：
Solution (C++):
int singleNonDuplicate(vector<int>& nums) {
int n = nums.size();
int low = 0, high = n - 1;
while (low < high) {
int mid = low + (high - low) / 2;
if (mid%2 == 0) {
if (nums[mid] == nums[mid-1]) high = mid - 2;
else if (nums[mid] == nums[mid+1]) low = mid + 2;
else return nums[mid];
} else {
if (nums[mid] == nums[mid-1]) low = mid + 1;
else if (nums[mid] == nums[mid+1]) high = mid - 1;
}
}
return nums[low];
}
性能：
Runtime: 8 ms Memory Usage: 7.5 MB
思路：
Solution (C++):
性能：
Runtime: ms Memory Usage: MB
