Recursive solution to a task

recursive_squares.ts

export class G964 {
  public static decompose = (n: number) => {
    const decomposeWithIndex = (rest: number, index: number, currentResult = []) => {
      if (index < 0) {
        return null;
      }

      if (index * index > rest) {
        return decomposeWithIndex(rest, index - 1, currentResult);
      }


      if (index * index === rest) {
        return [index, ...currentResult];
      }

      // index * index < rest

      const localAnswer = decomposeWithIndex(rest - index * index, index - 1, [index, ...currentResult]);
      if (localAnswer === null) {
        return decomposeWithIndex(rest, index - 1, currentResult);         
      }

      return localAnswer;
    }
    
    return decomposeWithIndex(n * n, n - 1);
  }
}