lesson 09

lesson_09/binary_search.py

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+from random import randint
+
+
+def binary_search(array, key_value, left=0, right=None):
+    if right is None:
+        right = len(array)
+
+    middle = (left + right) // 2
+    while array[middle] != key_value and left <= right:
+        if array[middle] < key_value:
+            left = middle + 1
+        else:
+            right = middle - 1
+
+        middle = (left + right) // 2
+
+    return (True, middle) if not (left > right) else (False, middle+1)
+
+
+# Creating a sorted list of random values
+lst = []
+for i in range(15):
+    lst.append(randint(1, 50))
+lst.sort()
+print(lst)
+
+key = 23
+flag, idx = binary_search(lst, key)
+
+print('Flag =', flag)
+print('Index =', idx)
+
+# if key value not found, we can insert this value by index
+if not flag:
+    lst.insert(idx, key)
+
+print(lst)

lesson_09/bubble_sort.py

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+import random
+
+
+def bubble_sort(my_list):
+    cnt = 0
+    for i in range(len(my_list)-1):
+        cnt += 1
+        flag = True
+        for j in range(len(my_list)-1-i):
+            if my_list[j] > my_list[j+1]:
+                my_list[j], my_list[j+1] = my_list[j+1], my_list[j]
+                flag = False
+
+        if flag:
+            break
+
+    return cnt
+
+
+lst = [random.randint(10, 99) for _ in range(30)]
+print(lst)
+res = bubble_sort(lst)
+print(res)
+print(lst)

lesson_09/line_search.py

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+import random
+
+lst = [random.randint(10, 99) for _ in range(30)]
+print(lst)
+
+key = int(input('Please enter a value: '))
+
+for idx in range(len(lst)):
+    if lst[idx] == key:
+        print('idx =', idx)
+        break

lesson_09/quick_sort.py

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+import random
+
+
+def quick_sort(array, first_idx, last_idx):
+    if first_idx >= last_idx:
+        return
+
+    i, j = first_idx, last_idx
+    middle_value = array[(first_idx + last_idx) // 2]
+    while i <= j:
+        while array[i] < middle_value:
+            i += 1
+
+        while array[j] > middle_value:
+            j -= 1
+
+        if i <= j:
+            array[i], array[j] = array[j], array[i]
+            i, j = i+1, j-1
+
+    quick_sort(array, first_idx, j)
+    quick_sort(array, i, last_idx)
+
+
+lst = [random.randint(10, 99) for _ in range(30)]
+print(lst)
+quick_sort(lst, 0, len(lst)-1)
+print(lst)

lesson_09/recursion.py

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+
+def pow_iter(num, ex):
+    res = 1
+    while ex > 0:
+        res *= num
+        ex -= 1
+
+    return res
+
+
+def pow_rec(num, ex):
+    if ex == 0:
+        return 1
+
+    return num * pow_rec(num, ex-1)
+
+
+print(pow_iter(2, 4))
+print(pow_rec(2, 4))
+
+
+def fact_iter(num):
+    res = 1
+    for i in range(1, num+1):
+        res *= i
+
+    return res
+
+
+def fact_rec(num):
+    if num == 1:
+        return 1
+
+    return num * fact_rec(num-1)
+
+
+print(fact_iter(5))
+print(fact_rec(5))
+
+
+def fib_iter(num):
+    n1 = 0
+    n2 = 1
+    while num > 1:
+        res = n1 + n2
+        n1 = n2
+        n2 = res
+        num -= 1
+
+    return n2
+
+
+def fib_rec(num):
+    # if num == 0 or num == 1:
+    #     return num
+
+    return num if num == 0 or num == 1 else fib_rec(num-1) + fib_rec(num-2)
+
+
+print(fib_iter(14))
+print(fib_rec(14))