Minimum Stack

Author: saurabhchris1

Min_Stack.py

@@ -0,0 +1,46 @@
+# Design a stack that supports push, pop, top, and retrieving the minimum element in constant time.
+#
+# push(x) -- Push element x onto stack.
+# pop() -- Removes the element on top of the stack.
+# top() -- Get the top element.
+# getMin() -- Retrieve the minimum element in the stack.
+#
+# MinStack minStack = new MinStack();
+# minStack.push(-2);
+# minStack.push(0);
+# minStack.push(-3);
+# minStack.getMin();   --> Returns -3.
+# minStack.pop();
+# minStack.top();      --> Returns 0.
+# minStack.getMin();   --> Returns -2.
+
+
+class MinStack:
+
+    def __init__(self):
+        """
+        initialize your data structure here.
+        """
+        self.stack = []
+
+    def push(self, x):
+        if len(self.stack) == 0:
+            self.stack.append([x, x])
+        else:
+            self.stack.append([x, min(self.stack[-1][1], x)])
+
+    def pop(self):
+        self.stack.pop()
+
+    def top(self):
+        return self.stack[-1][0]
+
+    def getMin(self):
+        return self.stack[-1][1]
+
+# Your MinStack object will be instantiated and called as such:
+# obj = MinStack()
+# obj.push(x)
+# obj.pop()
+# param_3 = obj.top()
+# param_4 = obj.getMin()