js中数组reduce的两道题，求解答

Question

1.三个数组
[1,2,3],[4,5],[6,7]
展开为
145,147,156,157,246.....

2.数组对象
[{name:'a',children:[{name:'a-1'}]},{name:'b',children:[{name:'b-1'}]}] 
展开为
[{name:'a'},{name:'a-1'},{name:'b'},{name:'b-1'}]