将字符串数组的数组转换为分层结构

const input = [
  ['A', 'B'],
  ['A', 'C'],
  ['B', 'D'],
  ['B', 'E'],
  ['C', 'F']
];

{
  "A": {
    "B": {
      "D": {},
      "E": {}
    },
    "C": {
      "F": {}
    }
  }
}

function buildHierarchy(arr) {
  const result = {};

  arr.forEach(([parent, child]) => {
    if (!result[parent]) {
      result[parent] = {};
    }
    if (!result[parent][child]) {
      result[parent][child] = {};
    }
  });

  return result;
}

const input = [
  ['A', 'B'],
  ['A', 'C'],
  ['B', 'D'],
  ['B', 'E'],
  ['C', 'F']
];

const hierarchy = buildHierarchy(input);
console.log(JSON.stringify(hierarchy, null, 2));