Binary Tree Coloring Game LeetCode solution in Java

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class Solution {
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  int xkaLeft = 0, xkaRight = 0;
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  public int size(TreeNode node, int x) {
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    if (node == null) {
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      return 0;
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    }
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    int ls = size(node.left, x);
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    int rs = size(node.right, x);
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    if (node.val == x) {
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      xkaLeft = ls;
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      xkaRight = rs;
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    }
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    return ls + rs + 1;
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  }
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  public boolean btreeGameWinningMove(TreeNode root, int n, int x) {
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    size(root, x);
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    int parent = n - (xkaLeft + xkaRight + 1);
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    int max = Math.max(parent, Math.max(xkaRight, xkaLeft));
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    if (max > n / 2) {
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      return true;
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    }
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    return false;
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  }
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}