{"cells":[{"cell_type":"markdown","metadata":{},"source":"The BSTree data structure\n=========================\n\n"},{"cell_type":"markdown","metadata":{},"source":["## Agenda\n\n"]},{"cell_type":"markdown","metadata":{},"source":["-   API\n-   Implementation\n\n-   Search\n-   Addition\n-   Removal\n-   Iteration / Traversal\n\n"]},{"cell_type":"markdown","metadata":{},"source":["## API\n\n"]},{"cell_type":"code","execution_count":1,"metadata":{},"outputs":[],"source":["class BSTree:\n    class Node:\n        def __init__(self, val, left=None, right=None):\n            self.val = val\n            self.left = left\n            self.right = right\n\n    def __init__(self):\n        self.size = 0\n        self.root = None\n\n    def add(self, val):\n        \"\"\"Adds `val` to this tree while maintaining BSTree properties.\"\"\"\n        assert(val not in self)\n        pass\n\n    def __contains__(self, val):\n        \"\"\"Returns `True` if val is in this tree and `False` otherwise.\"\"\"\n        pass\n\n    def __delitem__(self, val):\n        \"\"\"Removes `val` from this tree while maintaining BSTree properties.\"\"\"\n        assert(val in self)\n        pass\n\n    def __iter__(self):\n        \"\"\"Returns an iterator over all the values in the tree, in ascending order.\"\"\"\n        pass\n\n    def __len__(self):\n        return self.size\n\n    def pprint(self, width=64):\n        \"\"\"Attempts to pretty-print this tree's contents.\"\"\"\n        height = self.height()\n        nodes  = [(self.root, 0)]\n        prev_level = 0\n        repr_str = ''\n        while nodes:\n            n,level = nodes.pop(0)\n            if prev_level != level:\n                prev_level = level\n                repr_str += '\\n'\n            if not n:\n                if level < height-1:\n                    nodes.extend([(None, level+1), (None, level+1)])\n                repr_str += '{val:^{width}}'.format(val='-', width=width//2**level)\n            elif n:\n                if n.left or level < height-1:\n                    nodes.append((n.left, level+1))\n                if n.right or level < height-1:\n                    nodes.append((n.right, level+1))\n                repr_str += '{val:^{width}}'.format(val=n.val, width=width//2**level)\n        print(repr_str)\n\n    def height(self):\n        \"\"\"Returns the height of the longest branch of the tree.\"\"\"\n        def height_rec(t):\n            if not t:\n                return 0\n            else:\n                return max(1+height_rec(t.left), 1+height_rec(t.right))\n        return height_rec(self.root)"]},{"cell_type":"code","execution_count":1,"metadata":{},"outputs":[],"source":["t = BSTree()\nt.root = BSTree.Node(5,\n                    left=BSTree.Node(2),\n                    right=BSTree.Node(10))\nt.size = 3"]},{"cell_type":"code","execution_count":1,"metadata":{},"outputs":[],"source":["t.pprint()"]},{"cell_type":"code","execution_count":1,"metadata":{},"outputs":[],"source":["t.height()"]},{"cell_type":"markdown","metadata":{},"source":["## Implementation\n\n"]},{"cell_type":"markdown","metadata":{},"source":["### Search\n\n"]},{"cell_type":"code","execution_count":1,"metadata":{},"outputs":[],"source":["class BSTree(BSTree):\n    def __contains__(self, val):\n        pass"]},{"cell_type":"code","execution_count":1,"metadata":{},"outputs":[],"source":["t = BSTree()\nt.root = BSTree.Node(5,\n                    left=BSTree.Node(2),\n                    right=BSTree.Node(10))\nt.size = 3"]},{"cell_type":"code","execution_count":1,"metadata":{},"outputs":[],"source":["5 in t"]},{"cell_type":"markdown","metadata":{},"source":["### Addition\n\n"]},{"cell_type":"code","execution_count":1,"metadata":{},"outputs":[],"source":["class BSTree(BSTree):\n    def add(self, val):\n        assert(val not in self)\n        pass"]},{"cell_type":"code","execution_count":1,"metadata":{},"outputs":[],"source":["import random\nt = BSTree()\nvals = list(range(5))\nrandom.shuffle(vals)\nfor x in vals:\n    t.add(x)\nt.pprint()"]},{"cell_type":"markdown","metadata":{},"source":["### Removal\n\n"]},{"cell_type":"code","execution_count":1,"metadata":{},"outputs":[],"source":["class BSTree(BSTree):\n    def __delitem__(self, val):\n        assert(val in self)\n        # deal with relatively simple cases first!\n        pass"]},{"cell_type":"code","execution_count":1,"metadata":{},"outputs":[],"source":["t = BSTree()\nfor x in [10, 5, 15, 2, 17]:\n    t.add(x)\nt.pprint()"]},{"cell_type":"code","execution_count":1,"metadata":{},"outputs":[],"source":["del t[2]\nt.pprint()"]},{"cell_type":"code","execution_count":1,"metadata":{},"outputs":[],"source":["t = BSTree()\nfor x in [10, 5, 15, 2, 17]:\n    t.add(x)\nt.pprint()"]},{"cell_type":"code","execution_count":1,"metadata":{},"outputs":[],"source":["del t[5]\nt.pprint()"]},{"cell_type":"code","execution_count":1,"metadata":{},"outputs":[],"source":["t = BSTree()\nfor x in [10, 5, 15, 2, 17]:\n    t.add(x)\nt.pprint()"]},{"cell_type":"code","execution_count":1,"metadata":{},"outputs":[],"source":["del t[15]\nt.pprint()"]},{"cell_type":"code","execution_count":1,"metadata":{},"outputs":[],"source":["t = BSTree()\nfor x in [10, 5, 15, 2, 17]:\n    t.add(x)\nt.pprint()"]},{"cell_type":"code","execution_count":1,"metadata":{},"outputs":[],"source":["del t[10]\nt.pprint()"]},{"cell_type":"code","execution_count":1,"metadata":{},"outputs":[],"source":["class BSTree(BSTree):\n    def __delitem__(self, val):\n        # fully working delete\n        assert(val in self)\n        pass"]},{"cell_type":"code","execution_count":1,"metadata":{},"outputs":[],"source":["t = BSTree()\nfor x in [10, 5, 2, 7, 9, 8, 1, 15, 12, 18]:\n    t.add(x)\nt.pprint()"]},{"cell_type":"code","execution_count":1,"metadata":{},"outputs":[],"source":["del t[15]\nt.pprint()"]},{"cell_type":"code","execution_count":1,"metadata":{},"outputs":[],"source":["t = BSTree()\nfor x in [10, 5, 2, 7, 9, 8, 1, 15, 12, 18]:\n    t.add(x)\nt.pprint()"]},{"cell_type":"code","execution_count":1,"metadata":{},"outputs":[],"source":["del t[5]\nt.pprint()"]},{"cell_type":"code","execution_count":1,"metadata":{},"outputs":[],"source":["t = BSTree()\nfor x in [10, 5, 2, 7, 9, 8, 1, 15, 12, 18]:\n    t.add(x)\nt.pprint()"]},{"cell_type":"code","execution_count":1,"metadata":{},"outputs":[],"source":["del t[10]\nt.pprint()"]},{"cell_type":"markdown","metadata":{},"source":["### Iteration / Traversal\n\n"]},{"cell_type":"code","execution_count":1,"metadata":{},"outputs":[],"source":["class BSTree(BSTree):\n    def __iter__(self):\n        pass"]},{"cell_type":"code","execution_count":1,"metadata":{},"outputs":[],"source":["import random\nt = BSTree()\nvals = list(range(20))\nrandom.shuffle(vals)\nfor x in vals:\n    t.add(x)\nfor x in t:\n    print(x)"]}],"metadata":{"org":null,"kernelspec":{"display_name":"Python 3","language":"python","name":"python3"},"language_info":{"codemirror_mode":{"name":"ipython","version":3},"file_extension":".py","mimetype":"text/x-python","name":"python","nbconvert_exporter":"python","pygments_lexer":"ipython3","version":"3.5.2"}},"nbformat":4,"nbformat_minor":0}