add min-stack

tg123 · tg123 · commit 60097a48532e · 2014-11-12T12:26:56.000+08:00
diff --git a/min-stack/MinStack.java b/min-stack/MinStack.java
@@ -0,0 +1 @@
+Solution.java
diff --git a/min-stack/README.md b/min-stack/README.md
diff --git a/min-stack/Solution.java b/min-stack/Solution.java
@@ -0,0 +1,66 @@
+class MinStack {
+
+    static class Stack {
+
+        static class Node {
+            int val;
+            Node next;
+            Node prev;
+        }
+
+        Node head = new Node();
+        int size = 0;
+
+        public void push(int x) {
+            Node n = new Node();
+            n.val = x;
+            n.prev = head;
+
+            head.next = n;
+            head = n;
+
+            size++;
+        }
+
+        public void pop() {
+            head = head.prev;
+            size--;
+        }
+
+        public int top() {
+            return head.val;
+        }
+    }
+
+    Stack data = new Stack();
+    Stack mins = new Stack();
+
+    public void push(int x) {
+        data.push(x);
+
+        if(mins.size == 0 || getMin() >= x){
+            mins.push(x);
+        }
+    }
+
+    public void pop() {
+        int last = data.top();
+        data.pop();
+
+        if(last <= getMin()){
+            mins.pop();
+        }
+    }
+
+    public int top() {
+        return data.top();
+    }
+
+    public int getMin() {
+        if(mins.size > 0){
+            return mins.top();
+        }
+
+        throw new IllegalStateException();
+    }
+}
diff --git a/min-stack/index.md b/min-stack/index.md
@@ -0,0 +1,8 @@
+---
+layout: solution
+title: Min Stack
+date: 2014-11-12 12:19:55+08:00
+---
+{% assign leetcode_name = {{page.path | remove: '/index.md'}}  %}
+{% assign leetcode_readme = {{leetcode_name | append: '/README.md' | prepend: '_root/' }}  %}
+{% include {{leetcode_readme}} %}
