请问这个小算法题怎么解？

Question

let a = {

        'aa':[{
            name:'zs',

            num:10

        },{
            name:'lisi',

            num:11

        }],

        'bb':[{
            name:'zs',

            num:12

        },{
            name:'lisi',

            num:13

        }],

        'ccc':[{
            name:'zs',

            num:14

        },{
            name:'lisi',

            num:15

        },{
            name:'ww',

            num:16

        }]

    }

想要分别求求aa bb ccc 中的 num值相加的和

Answer 1

const a = {        
    'aa':[
      {name:'zs',num:10},
      {name:'lisi',num:11}
     ],
    'bb':[
      {name:'zs',num:12},
      {name:'lisi',num:13}
     ],
    'cc':[
      {name:'zs',num:14},
      {name:'lisi',num:15}
     ],
}
const obj = {}
Object.keys(a).map((key)=>{
    obj[key] = a[key].reduce((sum,item)=> (sum += item.num), 0)
})

Answer 2

Object.values(a).reduce((sum, arr) => arr.reduce((sum, item) => sum + item.num, sum), 0)总和

Object.entries(a).reduce((res, [k, v]) => (res[k] = v.reduce((sum, item) => sum + item.num, 0), res), {})分别求和