warmup, preparing to give interviews

short_phone_interview_problems/hash_table.py

@@ -0,0 +1,45 @@
+#!/usr/bin/env python
+
+__author__ = "bt3"
+
+
+class HashTable(object):
+    def __init__(self, slots=10):
+        self.slots = slots
+        self.table = []
+        self.create_table()
+
+    # Get the slot
+    def hash_key(self, value):
+        return hash(value)%self.slots
+
+    # When creating the table, add list struct 
+    # to each slot
+    def create_table(self):
+        for i in range(self.slots):
+            self.table.append([])
+
+    # Method to add a item in the right slot
+    def add_item(self, value):
+        key = self.hash_key(value)
+        self.table[key].append(value)
+
+    # Aux: print table
+    def print_table(self):
+        for key in range(self.slots):
+            print "Key is {0}, value is {1}.".format(key, self.table[key])
+
+    # Aux: find item
+    def find_item(self, item):
+        item_hash = self.hash_key(item)
+        return item in self.table[item_hash]
+        
+
+if __name__ == '__main__':
+    dic = HashTable(5)
+    for i in range(1, 40, 2):
+        dic.add_item(i)
+
+    dic.print_table()
+    assert(dic.find_item(20) == False)
+    assert(dic.find_item(21) == True)

short_phone_interview_problems/linked_list.py

@@ -0,0 +1,60 @@
+#!/usr/bin/env python
+
+__author__ = "bt3"
+
+
+class Node(object):
+    def __init__(self, value, next=None):
+        self.value = value
+        self.next = next
+        
+
+class LinkedList(object):
+    def __init__(self):
+        self.head = None
+  
+      def _add(self, value):
+        self.head = Node(value, self.head)
+            
+    def _printList(self):
+        node = self.head
+        while node:
+            print node.value
+            node = node.next
+            
+    def _find(self, index):
+        prev = None
+        node = self.head
+        i = 0
+        while node and i < index:
+            prev = node
+            node = node.next
+            i += 1
+        return node, prev, i
+
+    def _delete(self, prev, node):
+        if not prev:
+            self.head = node.next
+        else:
+            prev.next = node.next
+    
+    def deleteNode(self, index):
+        node, prev, i = self._find(index)
+        if index == i:
+            self._delete(prev, node)
+        else:
+            print('Node with index {} not found'.format(index))
+
+    
+
+if __name__ == '__main__':
+    ll = LinkedList()
+    for i in range(1, 5):
+        ll._add(i)
+        
+    print('The list is:')
+    ll._printList()
+     
+    print('The list after deleting node with index 2:')
+    ll.deleteNode(2)
+    ll._printList()