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136. Single Number 👍

  • Time: $O(n)$
  • Space: $O(1)$
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class Solution {
 public:
  int singleNumber(vector<int>& nums) {
    int ans = 0;

    for (const int num : nums)
      ans ^= num;

    return ans;
  }
};

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class Solution {
  public int singleNumber(int[] nums) {
    int ans = 0;

    for (final int num : nums)
      ans ^= num;

    return ans;
  }
}

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class Solution:
  def singleNumber(self, nums: List[int]) -> int:
    return functools.reduce(operator.xor, nums, 0)