Week 6: Valid Parentheses

Author: mandel-17

valid-parentheses/mandel-17.py

@@ -0,0 +1,44 @@
+class ArrayStack:
+    def __init__(self, capacity):
+        self.capacity = capacity
+        self.array = [None] * self.capacity
+        self.top = -1
+    
+    def isEmpty(self):
+        return self.top == -1
+
+    def isFull(self):
+        return self.top == self.capacity - 1
+
+    def push(self, item):
+        if not self.isFull():
+            self.top += 1
+            self.array[self.top] = item
+        else:
+            pass
+
+    def pop(self):
+        if not self.isEmpty():
+            self.top -= 1
+            return self.array[self.top+1]
+        else:
+            pass
+
+class Solution:
+    def isValid(self, s: str) -> bool:
+        stack = ArrayStack(100)
+        for ch in s:
+            if ch in ('(', '[', '{'):
+                stack.push(ch)
+            elif ch in (')', ']', '}'):
+                if stack.isEmpty():
+                    return False
+                else:
+                    left = stack.pop()
+                    if (ch == ')' and left != '(') or \
+                       (ch == ']' and left != '[') or \
+                       (ch == '}' and left != '{'):
+                           return False
+        return stack.isEmpty()
+
+