@@ -0,0 +1,41 @@
+#!/usr/bin/env python3
+# encoding: utf-8
+from itertools import *
+
+def permutation(s):
+    for item in permutations(s):
+        if item:
+            print(''.join(i for i in item), end=' ') # abc acb bac bca cab cba
+    print('')
+
+def permutation2(s, i):
+    for item in permutations(s, i):
+        if item:
+            print(''.join(i for i in item), end=' ') # abc acb bac bca cab cba
+    print('')
+
+def permutation3(s, i):
+    for item in product(s, repeat=i):
+        if item:
+            print(''.join(i for i in item), end=' ') # abc acb bac bca cab cba
+    print('')
+
+def combination(s, i):
+    for item in combinations(s, i):
+        if item:
+            print(''.join(i for i in item), end=' ') # abc acb bac bca cab cba
+    print('')
+
+def combination2(s, i):
+    for item in combinations_with_replacement(s, i):
+        if item:
+            print(''.join(i for i in item), end=' ') # abc acb bac bca cab cba
+    print('')
+
+if __name__ == '__main__':
+    permutation('abc')
+    permutation('abb')
+    permutation2('abc', 2)
+    permutation3('abc', 2)
+    combination('abcd', 2)
+    combination2('abcd', 2)
@@ -0,0 +1,41 @@
+
+#!/usr/bin/env python3
+# encoding: utf-8
+#
+# Copyright (c) 2017 Vladimir Shurygin.  All rights reserved.
+#
+'''
+Dijkstra algorithm find shortest path in graph Shortest paths in graphs without negative edges.
+'''
+#add parent directory with base module
+import os
+from sys import path
+path.insert(0, os.path.abspath(os.path.join(os.path.dirname(__file__), '../bst')))
+
+from undirected_cyclic import Graph
+from vertex import Vertex
+from bst_heap_min import MinHeap
+
+def dijkstra_min_priority_queue(graph, start, finish):
+    ''' Implementation with min-priority queue
+    BigO = V**2, (where |V| is the number of nodes).
+    '''
+    if not isinstance(graph, Graph):
+        return None
+    if start is None:
+        return None
+    heap = MinHeap()
+    visited = {}
+    heap.push({'vertex':start.id, 'value':0})
+    path = {}
+    while heap.array:
+        obj = heap.pop()
+        vertex = graph.get_vertex(obj['vertex'])
+        if vertex.id in visited:
+            continue
+        for adj_vertex_id in vertex.adj:
+            adj_vertex = vertex.adj[adj_vertex_id]
+            edge_property = vertex.get_edge_property(adj_vertex_id)
+            heap.push({'vertex':adj_vertex, 'value':None})
+
+    pass