07-build_order.go

package treesandgraphs

// You are given a list of projects and a list of dependencies (which is
// a list of pairs of projects, where the second project is dependent on
// the first project). All of a project's dependencies must be built before
// the project is. Find a build order that will allow the projects to be
// built. If there is no valid build order, return an error.
//
// EXAMPLE Input:
// projects: a, b, c, d, e, f
//
// dependencies: (a, d), (f, b), (b, d), (f, a), (d, c)
//
// Output: f, e, a, b, d, c