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class Solution {
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  public int singleNumber(int[] nums) {
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    int[] bitCount = new int[32]; // 32 bit number
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    // Count occurrence of each bits in each num
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    for (int i = 0; i < bitCount.length; i++) {
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      for (int num : nums) {
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        if ((num & 1 << i) != 0) // If ith bit in "num" is 1
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        bitCount[i]++;
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      }
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    }
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    // Check the bit which doesn't have count multiple of 3 (i.e. no of repeating digits in input
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    // nums arr)
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    // and add it to the result.
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    int result = 0;
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    for (int i = 0; i < bitCount.length; i++) result += (bitCount[i] % 3) * (1 << i);
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    return result;
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  }
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}