LU-Factorization Algorithm??

[DeadxBunny]

Question: Develop an algorithm for finding directly the UL-factorization of a matrix A, where L is a unit lower triangular and U is upper triangular. Give an algorithm for solving ULx=b.

I'm not sure how to tackle this problem since the book already showed us how to do Doolittle's factorization and I'm assuming they want a different method of doing the same thing..

Thanks in advance for your help!