<script>
    function findNum(nums) {
      let result = nums[0];
      for (let i = 1; i < nums.length; i++) {
        result = result ^ nums[i];
      }
      return result;
    }

    arr = [1, 2, 2, 4, 6, 1, 1, 3, 4, 3, 6];
    console.log(findNum(arr))
  </script>

时间复杂度：O(n)
空间复杂度：O(1)