第 125 期(算法-递归)：统计子类目数量 #128
Description
已知数据如下：
const testData = [
{
name: '大中华区',
type: 'area',
children: [
{
name: '华北片区',
type: 'region',
children: [
{
name: '北京',
type: 'city',
children: [
{
name: '东城区',
type: 'district',
children: [
{ name: '东华门街道专卖店', type: 'store' },
{ name: '东四街门店', type: 'store' },
{ name: '和平里专卖店', type: 'store' }
]
}, {
name: '朝阳区',
type: 'district',
children: [
{ name: '亚运村旗舰店', type: 'store' },
{ name: '朝外街道店', type: 'store' }
]
}
]
}
]
}, {
name: '华东片区',
type: 'region',
children: [
{
name: '上海',
type: 'city',
children: [
{
name: '黄浦区',
type: 'district',
children: [
{ name: '佳佳旗舰店', type: 'store' }
]
}
]
}, {
name: '青岛',
type: 'city',
children: [
{
name: '黄岛区',
type: 'district',
children: [
{ name: '蜊叉泊商业街门店', type: 'store' }
]
}
]
}
]
}
]
}, {
name: '海外大区',
type: 'area',
children: [
{
name: '欧洲',
type: 'region',
children: [
{
name: '巴黎',
type: 'city',
children: [
{
name: '第4区',
type: 'district',
children: [
{ name: '圣安东尼大道旗舰店', type: 'store' }
]
}
]
}
]
}
]
}
];请统计总的 area、region、city、district 和 store 的数量，并统计每个大区（area）下 region、city、district 和 store 的数量。效果如下：
参考代码：
主要用到了递归思想和
reduce方法
const model = ['area', 'region', 'city', 'district', 'store'];
console.group('总计');
display(model, testData);
console.groupEnd();
testData.map(node => {
console.group(node.name);
display(model.slice(1), node.children);
console.groupEnd();
});
function countNumber(type, data) {
const _count = (arr) => {
if (!(Array.isArray(arr) && arr.length)) {
return 0;
}
if (arr[0].type === type) {
return arr.length;
}
return arr.reduce((total, cur) => {
return total + _count(cur.children);
}, 0);
};
return _count(data);
}
function display(model, data) {
model.map(s => {
const title = s.substr(0, 1).toUpperCase() + s.substr(1);
const number = countNumber(s, data);
console.log(`${title}: ${number}`);
});
}