Added W06 materials

README.md

@@ -44,8 +44,8 @@
 | 03     | Basic Data sturctures  | [Slides][Slides_W03] | [Test][WarmUp_test_W03] | [Contest][ContestID_W03] | 28.10.2024 19:00 UTC+3 |
 | 04     | Dynamic programming    | [Slides][Slides_W04] | [Test][WarmUp_test_W04] | [Contest][ContestID_W04] | 04.11.2024 19:00 UTC+3 |
 | 05     | Knapsack problem       | [Slides][Slides_W05] | [Test][WarmUp_test_W05] | [Contest][ContestID_W05] | 11.11.2024 19:00 UTC+3 |
+| 06     | KMP & Heap             | [Slides][Slides_W06] | [Test][WarmUp_test_W06] | [Contest][ContestID_W06] | 18.11.2024 19:00 UTC+3 |
 <!---
-| 06     | KMP & Heap             | [Slides][Slides_W06] | [Test][WarmUp_test_W06] | [Contest][ContestID_W06] | ??.11.2024 19:00 UTC+3 |
 | 07     | DFS & BFS              | [Slides][Slides_W07] | [Test][WarmUp_test_W07] | [Contest][ContestID_W07] | ??.12.2024 19:00 UTC+3 |
 | 08     | Shortest paths         | [Slides][Slides_W08] | [Test][WarmUp_test_W08] | [Contest][ContestID_W08] | ??.12.2024 19:00 UTC+3 |
 | 09     | RSQ & RMQ              | [Slides][Slides_W09] | [Test][WarmUp_test_W09] | [Contest][ContestID_W09] | ??.12.2024 19:00 UTC+3 |

week06_kmp_heap/heap.py

@@ -0,0 +1,51 @@
+import random
+
+
+def sift_up(data, i):
+    if i == 0:
+        return
+    parent = (i - 1) // 2
+    if data[parent] > data[i]:
+        data[parent], data[i] = data[i], data[parent]
+        sift_up(data, parent)
+
+
+def sift_down(data, i):
+    child1 = i * 2 + 1
+    child2 = i * 2 + 2
+    if child1 >= len(data):
+        return
+    if child2 >= len(data):
+        child_min = child1
+    else:
+        child_min = child1 if data[child1] < data[child2] else child2
+    if data[child_min] < data[i]:
+        data[i], data[child_min] = data[child_min], data[i]
+        sift_down(data, child_min)
+
+
+def heapify(data):
+    for i in range(len(data) - 1, -1, -1):
+        sift_down(data, i)
+
+
+def heappush(data, x):
+    data.append(x)
+    sift_up(data, len(data) - 1)
+
+
+def heappop(data, i=0):
+    data[i], data[-1] = data[-1], data[i]
+    res = data.pop()
+    sift_up(data, i)
+    sift_down(data, i)
+    return res
+
+
+if __name__ == '__main__':
+    n = random.randint(0, 100)
+    h = [random.randint(0, 1000) for i in range(n)]
+
+    heapify(h)
+    while len(h) > 0:
+        print(heappop(h))

week06_kmp_heap/substring.py

@@ -0,0 +1,55 @@
+def find_substrings_naive(s, p):
+    N = len(s)
+    K = len(p)
+    substrings = []
+    for i in range(N - K + 1):
+        if all([s[i + j] == p[j] for j in range(K)]):
+            substrings.append(i)
+    return substrings
+
+
+def prefix_function(s):
+    d = [0] * (len(s) + 1)
+    for i in range(2, len(d)):
+        d[i] = d[i - 1]
+        while s[i - 1] != s[d[i]] and d[i] > 0:
+            d[i] = d[d[i]]
+        if s[i - 1] == s[d[i]]:
+            d[i] += 1
+    return d
+
+
+def find_substrings_kmp(s, p):
+    substrings = []
+    d = prefix_function(p + '$' + s)
+    for i in range(len(p) + 1, len(d)):
+        if d[i] == len(p):
+            substrings.append(i - 2 * len(p) - 1)
+    return substrings
+
+
+def find_substrings_native(s, p):
+    i = -1
+    substrings = []
+    while True:
+        i = s.find(p, i + 1)
+        if i >= 0:
+            substrings.append(i)
+        else:
+            return substrings
+
+from time import time
+if __name__ == '__main__':
+    #s = input().strip()
+    #p = input().strip()
+    s = 'a' * 100000 + 'b'
+    p = 'a' * 50000 + 'b'
+
+    t1 = time()
+    print('Python: ', ' '.join(map(str, find_substrings_native(s, p))))
+    t2 = time()
+    #print('Naive : ', ' '.join(map(str, find_substrings_naive(s, p))))
+    t3 = time()
+    print('KMP   : ', ' '.join(map(str, find_substrings_kmp(s, p))))
+    t4 = time()
+    print(f'{t2 - t1:.8f}, {t3 - t2:.8f}, {t4 - t3:.8f}')