Solved, using stack method of append and pop

NeetCodeRoadmap/Stack/20_Valid_Parenthesis.py

@@ -0,0 +1,26 @@
+def isValid(s):
+    """
+    :type s: str
+    :rtype: bool
+    """
+    stack = [] # only use append and pop
+    pairs = {
+        '(': ')',
+        '{': '}',
+        '[': ']'
+    }
+    for bracket in s:
+        if bracket in pairs:
+            stack.append(bracket)
+        elif len(stack) == 0 or bracket != pairs[stack.pop()]: # Checks for corresponding dictionary value based on previous closing bracket
+            return False
+        print(stack)
+    return len(stack) == 0
+
+
+
+# print(isValid("()")) # true
+print(isValid("()[]{}")) # true
+print(isValid("(]")) # false
+print(isValid("([)]")) # false
+print(isValid("{[]}")) # true

Top150Interview/20_Valid_Parenthesis.py

@@ -1,31 +0,0 @@
-def isValid(s):
-    """
-    :type s: str
-    :rtype: bool
-    """
-    pervious = ""
-    openBracket = ['(', '{', '[']
-    bracketPairs = ['()', '{}', '[]']
-    pairs = None
-
-    for x in s:
-        if x in openBracket:
-            previous = x
-        else:
-            # print(previous+x)
-            if (previous+x) in bracketPairs:
-                pairs = True
-            else:
-                return False
-    return pairs
-
-print(isValid("()"))
-print(isValid("()[]{}"))
-print(isValid("(]"))
-print(isValid("([)]"))
-print(isValid("{[]}"))
-print(isValid("{[]}"))
-print(isValid("{[]}"))
-print(isValid("{[]}"))
-print(isValid("{[]}"))
-print(isValid("{[]}"))