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class Solution {
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  public int waysToMakeFair(int[] nums) {
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    int esum = 0; // Sum of even-indexed elements
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    int osum = 0; // Sum of odd-indexed elements
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    int n = nums.length;
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    for (int i = 0; i < n; i++) {
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      if (i % 2 == 0) {
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        osum += nums[i];
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      } else {
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        esum += nums[i];
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      }
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    }
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    int count = 0;
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    int prev = 0;
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    for (int i = 0; i < n; i++) {
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      if (i % 2 == 0) {
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        osum = osum - nums[i] + prev;
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      } else {
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        esum = esum - nums[i] + prev;
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      }
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      if (esum == osum) {
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        count++;
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      }
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      prev = nums[i];
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    }
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    return count;
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  }
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}