1 files changed, 188 insertions, 0 deletions
diff --git a/ass2/q2/new_suffix_array.py b/ass2/q2/new_suffix_array.py
new file mode 100644
index 0000000..0c97137
--- /dev/null
+++ b/ass2/q2/new_suffix_array.py
@@ -0,0 +1,188 @@
+import sys
+
+
+class Node:
+    global_end = 0
+    all_nodes = []
+    string = ""
+
+    def __init__(self, start, end, root=False):
+        self.root = root
+        self.start = start
+        self.end = end
+        self.children = {}
+        self.id = len(self.all_nodes)
+        self.all_nodes.append(self)
+        self.parent = None
+        self.link = None
+
+    def __str__(self):
+        link_str = "" if self.link is None else f" -> {self.link.id}"
+        if not self.root:
+            j, i = self.tuple()
+            return f"[{self.id}, {self.tuple()}, {self.string[j:i + 1]}{link_str}]"
+        return f"[{self.id} root{link_str}]"
+
+    def __repr__(self):
+        return f"[{self.id}]"
+
+    def print_tree(self, spaces=1):
+        print(f"{self}")
+        for edge in self.children:
+            print(f"   " * spaces, end="")
+            self.get_child(edge).print_tree(spaces=spaces + 1)
+
+    def first_char(self):
+        return self.string[self.start]
+
+    def get_child(self, char):
+        if char in self.children:
+            return self.children[char]
+        return None
+
+    def add_child(self, child):
+        child.parent = self
+        self.children[child.first_char()] = child
+        return child
+
+    def remove_child(self, child):
+        self.children.pop(child)
+
+    @property
+    def end_index(self):
+        return self.tuple()[1]
+
+    def tuple(self):
+        if self.root:
+            raise Exception("Can't get substring of root.")
+        if self.end == "#":
+            return self.start, self.global_end
+        return self.start, self.end
+
+    @property
+    def edge_length(self):
+        if self.root:
+            return 0
+        else:
+            start, end = self.tuple()
+            return end - start + 1
+
+    def detach(self):
+        self.parent.remove_child(self)
+        self.parent = None
+
+
+class Point:
+    def __init__(self, node, edge="", length=0):
+        assert isinstance(node, Node)
+        self.node = node
+        self.edge = edge
+        self.length = length
+
+    def __repr__(self):
+        return f"(Node {self.node.id}'s edge:'{self.edge}', {self.length} along.)"
+
+    def is_explicit(self):  # a.k.a. is not on an edge
+        return self.edge == ""
+
+    def set_node(self, node):
+        self.node = node
+        self.edge = ""
+        self.length = 0
+        if not self.is_explicit():
+            print("WARNING: Node.set_node", file=sys.stderr)
+
+    @property
+    def edge_node(self) -> Node:
+        return self.node.get_child(self.edge)
+
+    def index_here(self):
+        if self.node.root:
+            return None
+        if self.is_explicit():
+            return self.node.start
+        return self.edge_node.start + self.length - 1
+
+    def char_here(self):
+        return Node.string[self.index_here()]
+
+
+def create_root():
+    assert len(Node.all_nodes) == 0
+    return Node(None, None, root=True)
+
+
+def do_phase(root: Node, active: Point, i, last_j):
+    root_point = Point(root)
+    Node.global_end += 1
+    did_rule_three = False
+    j = last_j + 1
+    while not did_rule_three:
+        curr_char = Node.string[i]
+        new_point = skip_count(i + 1, root_point)
+
+
+def char_is_after(point: Point, char):
+    if point.is_explicit():
+        return char in point.node.children
+    else:
+        if point.length < point.node.edge_length:  # If not at the end of an edge
+            return Node.string[point.index_here() + point.length]
+        return None
+
+
+def skip_count(num_chars, start_point: Point):
+    incoming_length = -1
+    existing_length = 0
+    head = start_point
+    chars_left = num_chars
+    char = ""
+
+    if not head.is_explicit():
+        incoming_length = head.edge_node.edge_length - head.length
+        if num_chars < incoming_length:
+            head.length += num_chars
+            return head
+        head.set_node(head.edge_node)
+        chars_left -= incoming_length
+
+    direction = Node.string[0] if head.node.root else Node.string[head.node.end_index + 1]
+    # next_node = head.node.get_child(direction)
+    # incoming_length = next_node.edge_length
+    #
+    # chars_left -= incoming_length
+    # head.set_node(next_node)
+
+    while chars_left > incoming_length:
+        direction = Node.string[0] if head.node.root else Node.string[head.node.end_index + 1]
+        next_node = head.node.get_child(direction)
+        incoming_length = next_node.edge_length
+        if chars_left <= incoming_length:
+            break
+        chars_left -= incoming_length
+        head.set_node(next_node)
+
+
+    if chars_left > 0:  # Landed on an edge
+        head.edge = direction
+        head.length = chars_left
+
+    return head
+
+
+def ukkonen(string):
+    Node.string = string
+    # string += "$"
+    n = len(string)
+    remainder = 0
+    last_j = 1
+    root = create_root()
+    root.add_child(Node(0, 3)).add_child(Node(4, 6)).add_child(Node(7, 7)).add_child(Node(8, "#"))
+    root.add_child(Node(1, 6))
+    active = Point(root)
+    Node.global_end = len(string)
+    root.print_tree()
+    print(skip_count(151, Point(root, "a", 2)))
+
+
+ukkonen("abcdefghijklmnop$")