2023-02-21 Daily Challenge

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In: DailyChallenge

Today I have done leetcode's February LeetCoding Challenge with cpp.

February LeetCoding Challenge 21

Description

Single Element in a Sorted Array

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 <= 105
  • 0 <= nums[i] <= 105

Solution

auto speedup = [](){
  cin.tie(nullptr);
  cout.tie(nullptr);
  ios::sync_with_stdio(false);
  return 0;
}();
class Solution {
public:
  int singleNonDuplicate(vector<int>& nums) {
    int low = 0;
    int high = nums.size() - 1;
    while(low < high - 1) {
      int mid = (low + high) >> 1;
      mid ^= (mid & 1);
      if(nums[mid] == nums[mid + 1]) {
        low = mid + 1;
      } else {
        high = mid;
      }
    }
    return nums[high];
  }
};

// Accepted
// 15/15 cases passed (25 ms)
// Your runtime beats 82.58 % of cpp submissions
// Your memory usage beats 16.37 % of cpp submissions (22.4 MB)
Algorithm