Add some cool queue, stacks, strings, math, bit manipulation examples (#35)

stacks_and_queues/Queue.py

@@ -0,0 +1,120 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+# author: bt3gl
+
+import heapq
+
+
+class Queue:
+
+    def __init__(self):
+        self._in = []
+        self._out = []
+
+    ######################
+    #   Private methods
+    ######################
+    def _transfer_in_to_out(self):
+        while self._in:
+            self._out.append(self._in.pop())
+    
+    def __repr__(self):
+        if not self._out:
+            self._transfer_in_to_out()
+        
+        return f'{self._out}'
+
+    ######################
+    #  Properties
+    ######################
+    @property
+    def size(self):
+        return len(self._in) + len(self._out)
+    
+    @property
+    def peek(self):
+        if not self._out:
+            self._transfer_in_to_out()
+        if self._out:
+            return self._out[-1]
+        else:
+            print('❌ Queue is empty, cannot peek.')
+    
+    @property
+    def is_empty(self):
+        return not (bool(self._in) or bool(self._out))
+
+    ######################
+    #   Public methods
+    ######################
+    def enqueue(self, item):
+        self._in.append(item)
+
+    def dequeue(self):
+        if not self._out:
+            while self._in:
+                self.out.append(self._in.pop())
+
+        if self._out:
+             self._out.pop()
+        else:
+            print('❌ Queue is empty, cannot dequeue.')
+
+
+class PriorityQueue:
+
+    def __init__(self):
+        self.queue = []
+        self.index = 0
+    
+    def push(self, item, priority):
+        heapq.heappush(self.queue, (-priority, self.index, item))
+        self.index += 1
+    
+    def pop(self):
+        return heapq.heappop(self.queue)[-1]
+
+class Item:
+    
+    def __init__(self, name):
+        self.name = name
+
+    def __repr__(self):
+        return f'{self.name}'
+
+
+
+if __name__ == '__main__':
+
+    ######################
+    #   Simple Queue
+    ######################
+    print('🧪 Testing Queue...')
+    queue = Queue()
+    print(f"Is the queue empty? {queue.is_empty}")
+    print("Adding 1 to 10 in the queue...")
+    for i in range(1, 11):
+        queue.enqueue(i)
+    
+    print(f"Queue: {queue}")
+    print(f"\nQueue size: {queue.size}")
+    print(f"Queue peek : {queue.peek}")
+    print(f"Is the queue empty? {queue.is_empty}")
+    print(f"\nDequeue...")
+    queue.dequeue()
+    print(f"Queue: {queue}")
+    print(f"\nQueue size: {queue.size}")
+    print(f"Queue peek: {queue.peek}")
+    print(f"Is the queue empty? {queue.is_empty}")
+
+    ######################
+    #   Priority Queue
+    ######################
+    print('\n\n🧪 Testing Priority Queue...')
+    q = PriorityQueue()
+    q.push(Item('Item 1'), 1)
+    q.push(Item('Item 4'), 4)
+    q.push(Item('Item 3'), 3)
+    print(f"Priority Queue: {q.queue}")
+    print(f"Pop: {q.pop()}")
+    print(f"Priority Queue: {q.queue}")

stacks_and_queues/README.md

@@ -0,0 +1,59 @@
+## stacks and queues
+
+<br>
+
+### `Queues.py`
+
+<br>
+
+```python
+> python3 queues.py
+
+🧪 Testing Queue...
+Is the queue empty? True
+Adding 1 to 10 in the queue...
+Queue: [10, 9, 8, 7, 6, 5, 4, 3, 2, 1]
+
+Queue size: 10
+Queue peek : 1
+Is the queue empty? False
+
+Dequeue...
+Queue: [10, 9, 8, 7, 6, 5, 4, 3, 2]
+
+Queue size: 9
+Queue peek: 2
+Is the queue empty? False
+
+
+🧪 Testing Priority Queue...
+Priority Queue: [(-4, 1, Item 4), (-1, 0, Item 1), (-3, 2, Item 3)]
+Pop: Item 4
+Priority Queue: [(-3, 2, Item 3), (-1, 0, Item 1)]
+```
+
+<br>
+
+### `stack.py`
+
+<br>
+
+```python
+python3 stack.py
+
+Testing Stack...
+
+Stack: [12, 13, 14, 15, 16, 17, 18, 19, 20]
+Stack size: 9
+Stack peek: 20
+Stack is empty: False
+Stack min: 12
+
+Popping...
+20
+19
+18
+17
+16
+Stack: [12, 13, 14, 15]
+```

stacks_and_queues/Stack.py

@@ -0,0 +1,79 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+# author: bt3gl
+
+
+class Stack:
+
+    def __init__(self):
+        self.content = []
+        self.min_array = []
+        self.min = float('inf')
+
+    ######################
+    #   Private methods
+    ######################
+    def __repr__(self):
+        return f'{self.content}'
+
+    ######################
+    #  Properties
+    ######################
+    @property
+    def size(self):
+        return len(self.content)
+    
+    @property
+    def peek(self):
+        if self.content:
+            return self.content[-1]
+        else:
+            print('❌ Queue is empty, cannot peek.')
+    
+    @property
+    def is_empty(self):
+        return not bool(self.content)
+
+    ######################
+    #   Public methods
+    ######################
+    def push(self, value):
+        if value < self.min:
+            self.min = value
+
+        self.content.append(value)
+        self.min_array.append(self.min)
+    
+    def pop(self):
+        if self.content:
+            value = self.content.pop()
+            self.min_array.pop()
+            if self.min_array:
+                self.min = self.min_array[-1]
+            return value
+    
+    def find_min(self):
+        if self.min_array:
+            return self.min_array[-1]
+
+
+if __name__ == '__main__':
+
+    ######################
+    #   Simple Stack
+    ######################
+    print('Testing Stack...')
+    stack = Stack()
+    for i in range(12, 21):
+        stack.push(i)
+    
+    print(f'\nStack: {stack}')
+    print(f'Stack size: {stack.size}')
+    print(f'Stack peek: {stack.peek}')
+    print(f'Stack is empty: {stack.is_empty}')
+    print(f'Stack min: {stack.find_min()}')
+    
+    print('\nPopping...')
+    for i in range(5):
+        print(stack.pop())
+    print(f'Stack: {stack}')