Owing = false
Owed = false
pathTotal = 0

DFS(owing, friendship):
    for student in owing:
        student.color = white
        student.pred = null
        student.area = null

    for student in friendship:
        if student.color == white:
            DFS_VISIT(student, owing, friendship)

DFS_VISIT(student, owing, friendship)
    // Get all students current student is friends with
    for x in friendship:
        if x pair student:
            student.adj = student.adj + x

    // Check if adjacent members have not been visited
    for i in student.adj:
        if i.color != white:
            if owing[i] > 0:
                Owing = true
            else if owing[i] < 0:
                Owed = true

    // If it hasn't been visited
    if student.color == white:
        Owing = false
        Owed = false

        if student.pred == null:
            if owing[student] != 0:
                return "Failure"

        else:
            pathTotal = pathTotal + owing[student]

        // Calculated debt
        student.color = grey

    // Recursively go through the rest of the list
    for t in student.adj:
        if t.colot == white:
            t.pred = student
            DFS_VISIT(t, owing, friendship)

    // All neighbors visited
    student.color = black;