Adding Two Negabinary Numbers LeetCode solution in Java

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class Solution {
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  public int[] addNegabinary(int[] arr1, int[] arr2) {
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    List<Integer> result = new ArrayList();
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    int pointer_1 = arr1.length - 1;
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    int pointer_2 = arr2.length - 1;
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    int carry = 0;
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    int current = 0;
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    int sum = 0;
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    while (pointer_1 >= 0 || pointer_2 >= 0) {
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      int a = (pointer_1 >= 0) ? arr1[pointer_1] : 0;
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      int b = (pointer_2 >= 0) ? arr2[pointer_2] : 0;
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      sum = a + b + carry;
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      if (sum == 3) {
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        current = 1;
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        carry = -1;
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      } else if (sum == 2) {
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        current = 0;
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        carry = -1;
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      } else if (sum == 1) {
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        current = 1;
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        carry = 0;
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      } else if (sum == 0) {
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        current = 0;
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        carry = 0;
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      } else if (sum == -1) {
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        current = 1;
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        carry = 1;
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      }
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      result.add(current);
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      pointer_1--;
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      pointer_2--;
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    }
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    if (carry != 0) result.add(1);
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    if (carry == -1) result.add(1);
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    // Removing leading zeros
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    int idx = result.size() - 1;
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    while (idx > 0 && result.get(idx) == 0) idx--;
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    // reversing the list and adding the result to an array
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    int len = idx + 1;
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    int[] negaBinary = new int[len];
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    for (int i = 0; i < len; i++) {
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      negaBinary[i] = result.get(idx);
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      idx--;
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    }
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    return negaBinary;
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  }
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}