Kth Ancestor of a Tree Node LeetCode solution in JavaScript

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/**
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 * @param {number} n
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 * @param {number[]} parent
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 */
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let par;
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var TreeAncestor = function (n, parent) {
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  let p = new Array(n);
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  for (let i = 0; i < n; i++) {
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    p[i] = new Array(20);
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  }
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  for (let i = 0; i < n; i++) {
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    p[i][0] = parent[i];
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  }
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  for (let j = 1; j < 20; j++) {
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    for (let i = 0; i < n; i++) {
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      if (p[i][j - 1] == -1) {
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        p[i][j] = -1;
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      } else {
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        p[i][j] = p[p[i][j - 1]][j - 1];
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      }
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    }
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  }
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  par = p;
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};
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/**
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 * @param {number} node
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 * @param {number} k
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 * @return {number}
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 */
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TreeAncestor.prototype.getKthAncestor = function (node, k) {
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  for (let i = 0; i < 20; i++) {
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    if ((k >> i) & 1) {
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      node = par[node][i];
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      if (node == -1) {
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        return -1;
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      }
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    }
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  }
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  return node;
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};
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/**
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 * Your TreeAncestor object will be instantiated and called as such:
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 * var obj = new TreeAncestor(n, parent)
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 * var param_1 = obj.getKthAncestor(node,k)
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 */