upd

algorithms/labs/lab7/code/1.py

@@ -0,0 +1,14 @@
+def greedy_change(n, coins):
+    result = []
+    for value, count in sorted(coins, key=lambda x: -x[0]):
+        while count > 0 and n >= value:
+            n -= value
+            count -= 1
+            result.append(value)
+    return result if n == 0 else None
+
+
+if __name__ == "__main__":
+    coins = [(10, 3), (5, 2), (2, 5), (1, 10)]
+    N = 28
+    print(greedy_change(N, coins))

algorithms/labs/lab7/code/2.py

@@ -0,0 +1,20 @@
+def greedy_thief(weights, values, M, K):
+    items = list(zip(weights, values))
+    items.sort(key=lambda x: x[1] / x[0], reverse=True)
+    cap = M * K
+    total_value = 0
+    chosen = []
+    for w, v in items:
+        if w <= cap:
+            chosen.append((w, v))
+            cap -= w
+            total_value += v
+    return total_value, chosen
+
+
+if __name__ == "__main__":
+    weights = [2, 3, 4, 5, 9, 7, 3]
+    values = [3, 4, 5, 8, 10, 7, 6]
+    M = 2
+    K = 10
+    print(greedy_thief(weights, values, M, K))

algorithms/labs/lab7/code/3.py

@@ -0,0 +1,26 @@
+import heapq
+
+
+def dijkstra(graph, start):
+    dist = {v: float("inf") for v in graph}
+    dist[start] = 0
+    pq = [(0, start)]
+    while pq:
+        d, v = heapq.heappop(pq)
+        if d > dist[v]:
+            continue
+        for u, w in graph[v]:
+            if dist[v] + w < dist[u]:
+                dist[u] = dist[v] + w
+                heapq.heappush(pq, (dist[u], u))
+    return dist
+
+
+if __name__ == "__main__":
+    graph = {
+        "Невский": [("Лиговский", 5), ("Гороховая", 3)],
+        "Лиговский": [("Московский", 7)],
+        "Гороховая": [("Московский", 4)],
+        "Московский": [],
+    }
+    print(dijkstra(graph, "Невский"))