Create README - LeetHub

Author: snowphone

0155-min-stack/README.md

@@ -0,0 +1,44 @@
+<h2><a href="https://leetcode.com/problems/min-stack">155. Min Stack</a></h2><h3>Medium</h3><hr><p>Design a stack that supports push, pop, top, and retrieving the minimum element in constant time.</p>
+
+<p>Implement the <code>MinStack</code> class:</p>
+
+<ul>
+	<li><code>MinStack()</code> initializes the stack object.</li>
+	<li><code>void push(int val)</code> pushes the element <code>val</code> onto the stack.</li>
+	<li><code>void pop()</code> removes the element on the top of the stack.</li>
+	<li><code>int top()</code> gets the top element of the stack.</li>
+	<li><code>int getMin()</code> retrieves the minimum element in the stack.</li>
+</ul>
+
+<p>You must implement a solution with <code>O(1)</code> time complexity for each function.</p>
+
+<p>&nbsp;</p>
+<p><strong class="example">Example 1:</strong></p>
+
+<pre>
+<strong>Input</strong>
+[&quot;MinStack&quot;,&quot;push&quot;,&quot;push&quot;,&quot;push&quot;,&quot;getMin&quot;,&quot;pop&quot;,&quot;top&quot;,&quot;getMin&quot;]
+[[],[-2],[0],[-3],[],[],[],[]]
+
+<strong>Output</strong>
+[null,null,null,null,-3,null,0,-2]
+
+<strong>Explanation</strong>
+MinStack minStack = new MinStack();
+minStack.push(-2);
+minStack.push(0);
+minStack.push(-3);
+minStack.getMin(); // return -3
+minStack.pop();
+minStack.top();    // return 0
+minStack.getMin(); // return -2
+</pre>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>-2<sup>31</sup> &lt;= val &lt;= 2<sup>31</sup> - 1</code></li>
+	<li>Methods <code>pop</code>, <code>top</code> and <code>getMin</code> operations will always be called on <strong>non-empty</strong> stacks.</li>
+	<li>At most <code>3 * 10<sup>4</sup></code> calls will be made to <code>push</code>, <code>pop</code>, <code>top</code>, and <code>getMin</code>.</li>
+</ul>