index.ts

interface TreeNode {
  capacity: number;
  children: TreeNode[];
}

const findAverage = (node: TreeNode): number => {
  let sum: number = 0,
    count: number = 0;

  let traverse = (node: TreeNode): void => {
    sum += node.capacity;
    count += 1;
    if (node.children.length) {
      for (let i: number = 0; i < node.children.length; i++) {
        traverse(node.children[i]);
      }
    }
  };

  traverse(node);

  sum -= node.capacity;
  count -= 1;

  if (sum <= 0 || count <= 0) return 0;
  return sum / count;
};

const findMinPower = (rootTreeNode: TreeNode): number => {
  let minPower = 0;
  let traverse = (node: TreeNode): void => {
    const average = findAverage(node);
    if (node.capacity < average) {
      minPower += average - node.capacity;
    }

    if (node.children) {
      for (let i: number = 0; i < node.children.length; i++) {
        traverse(node.children[i]);
      }
    }
  };

  traverse(rootTreeNode);

  return minPower;
};

const rootNode: TreeNode = {
  capacity: 100,
  children: [
    {
      capacity: 200,
      children: [
        {
          capacity: 300,
          children: [
            {
              capacity: 500,
              children: [],
            },
            {
              capacity: 400,
              children: [],
            },
          ],
        },
      ],
    },
  ],
};

console.log(findMinPower(rootNode));