They asked me to write a rate limiting function from scratch, to deflate an array into a multi-layered JSON, and to find a split that makes a subarray sum to the same value.

Please write a rate limiting function

Given [{id: 1, pid: 0}, {id:2, pid:1}, {id: 3, pid:2}], deflate this into: [{id:1, children:[{id:2, children:[]}, {id:3, children:[]}]]