initial commit

codes/core/dijkstra/heap_dijkstra.py

@@ -0,0 +1,46 @@
+class DijkstraStats:
+    def __init__(self):
+        self.extract_min_calls = 0
+        self.relax_attempts = 0
+        self.relax_success = 0
+        # self.decrease_key_calls = 0
+        # self.add_calls = 0
+
+def heap_dijkstra(nodes, adj, heap, start, end):
+    INF = float('inf')
+    dist = [INF] * nodes
+    visited = [False] * nodes
+    stats = DijkstraStats()
+
+    dist[start] = 0
+
+    for v in range(nodes):
+        heap.add(v, dist[v])
+        # stats.add_calls += 1
+    
+    while True:
+        res = heap.extract_min()
+        stats.extract_min_calls += 1
+        if res is None:
+            break
+        cur, cur_dist = res
+
+        if cur_dist == INF:
+            break
+
+        if cur == end:
+            break
+
+        for nxt, d in adj[cur]:
+            stats.relax_attempts += 1
+            if visited[nxt]:
+                continue
+            new = cur_dist + d
+            if new < dist[nxt]:
+                stats.relax_success += 1
+                dist[nxt] = new
+                heap.decrease_key(nxt, new)
+        
+        visited[cur] = True
+    
+    return dist[end], stats

codes/core/dijkstra/pure_dijkstra.py

@@ -0,0 +1,32 @@
+def pure_dijkstra(nodes, adj, start, end):
+    dist = [float('inf')] * nodes
+    dist[start] = 0
+    visited = [False] * nodes
+
+    cur = start
+    
+    while True:
+        if cur == -1:
+            break
+
+        if cur == end:
+            break
+
+        for next, d in adj[cur]:
+            if not visited[next]:
+                new = dist[cur] + d
+                if new < dist[next]:
+                    dist[next] = new
+        
+        visited[cur] = True
+        
+        # Finding min node
+        min_node = -1
+        min_val = float('inf')
+        for n in range(nodes):
+            if not visited[n] and dist[n] < min_val:
+                min_node = n
+                min_val = dist[n]
+        cur = min_node
+    
+    return dist[end]