Which branch of the tree is bigger?

compare-branches.js

function compareBranches(arr) {
  // Helper function to traverse the tree recursively
  function sum(node) {
    if (!node) {
      return 0;
    }
    return node + sum(arr.shift() && arr.shift() ? node * 2 : null) + sum(arr.shift() && arr.shift() ? node * 2 + 1 : null);
  }

  const leftSum = sum(arr.shift());
  const rightSum = sum(arr.shift());
  
  if (leftSum > rightSum) {
    return "Left";
  } else if (rightSum > leftSum) {
    return "Right";
  } else {
    return "";
  }
}

// test cases
/** 
Input: arr: [3, 6, 2, 9, -1, 10]
Expected Output: "Left"

Input: arr: [1, 4, 100, 5]
Expected Output: "Right"

Equal branches
Input: arr: [1, 10, 5, 1, 0, 6]
Expected Output: ""

Empty tree
Input: arr: []
Expected Output: ""

Only root branch
Input: arr: [1]
Expected Output: ""

*/