function transformArr(arr){
    let indexes = arr.map((_, i) => i);
    indexes.sort((i1, i2) => arr[i2] - arr[i1]);

    let mainI = indexes[0];
    let relative = indexes.map(x => mainI - x);

    let res = {"main": arr[indexes[0]]};
    // let names = ['left', 'inner left', 'inner right', 'right'];
    let names = ['left', 'right'];
    for(let i = 1; i < relative.length; i++){
      let name = (0 < relative[i]) ? names.shift() : names.pop();
      let ind = indexes[i];
      res[name] = arr[ind];
    }
    return res;
  }