Merge pull request #423 from Kakarot-2000/master

Fixes #422

data_structures/graphs/Adjacency_matrix.py

@@ -4,10 +4,7 @@ def __init__(self, vertices, directed: bool):
         self.V = vertices
         self.e = 0
         self.d = directed
-        self.graph = []
-        for i in range(self.V):
-            lst = [0] * self.V
-            self.graph.append(lst)
+        self.graph = [[0 for i in range(vertices)] for j in range(vertices)]
 
     def add_edge(self, ver1, ver2):
         if self.d:
@@ -17,7 +14,7 @@ def add_edge(self, ver1, ver2):
             self.graph[ver2][ver1] = 1
 
     def remove_edge(self, ver1, ver2):
-        if self.d[ver1][ver2] == 0:
+        if self.graph[ver1][ver2] == 0:
             print("No edge between %d and %d" % (ver1, ver2))
             return
         if self.d:
@@ -30,6 +27,11 @@ def print_graph(self):
         for i in self.graph:
             print(i)
 
-
-
+if __name__=="__main__":
+    g1 = Graph(3,0)
+    g1.add_edge(0,0)
+    g1.add_edge(1,1)
+    g1.add_edge(2,2)
+    g1.remove_edge(2,1)
+    g1.print_graph()
 

data_structures/stack/balanced_expression.py

@@ -1,24 +1,30 @@
-# simple program to check if an expression is balanced using stack
 stack = []
 def checkBalanced(expr):
     for i in expr:
         if i == "{" or i == "[" or i == "(":
             stack.append(i)
         elif i == "}" or i == "]" or i == ")":
-            temp = stack.pop()
-            if i == "}" and temp != "{":
+            if not stack:
                 return False
-            elif i == "]" and temp != "[":
+            top = stack.pop()
+            if i == "}" and top != "{":
                 return False
-            elif i == ")" and temp != "(":
+            elif i == "]" and top != "[":
                 return False
+            elif i == ")" and top != "(":
+                return False
+        else:
+            print("Invalid Expression")
+            return False
 
-    return True
+    if not len(stack):
+        return True
+    else:
+        return False
 
 # main function
 expr = input()
-result = checkBalanced(expr)
-if result:
-    print("Expression is balanced")
+if not checkBalanced(expr):
+    print("Not Balanced")
 else:
-    print("Expression is not balanced")
+    print('Balanced')