feat: add python and java solutions to lcci question

添加《程序员面试金典》题解：面试题 03.02. 栈的最小值

Author: yanglbme

lcci/03.02.Min Stack/README.md

@@ -6,20 +6,87 @@
 
 ## 解法
 <!-- 这里可写通用的实现逻辑 -->
+利用辅助栈存放栈的最小元素。
 
 
 ### Python3
 <!-- 这里可写当前语言的特殊实现逻辑 -->
 
 ```python
+class MinStack:
 
+    def __init__(self):
+        """
+        initialize your data structure here.
+        """
+        self._s1 = []
+        self._s2 = []
+
+
+    def push(self, x: int) -> None:
+        self._s1.append(x)
+        self._s2.append(x if len(self._s2) == 0 or self._s2[-1] >= x else self._s2[-1])
+
+    def pop(self) -> None:
+        self._s1.pop()
+        self._s2.pop()
+
+    def top(self) -> int:
+        return self._s1[-1]
+
+    def getMin(self) -> int:
+        return self._s2[-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()
 ```
 
 ### Java
 <!-- 这里可写当前语言的特殊实现逻辑 -->
 
 ```java
+class MinStack {
+    private Stack<Integer> s1;
+    private Stack<Integer> s2;
+
+    /** initialize your data structure here. */
+    public MinStack() {
+        s1 = new Stack<>();
+        s2 = new Stack<>();
+    }
+    
+    public void push(int x) {
+        s1.push(x);
+        s2.push(s2.empty() || s2.peek() >= x ? x : s2.peek());
+    }
+    
+    public void pop() {
+        s1.pop();
+        s2.pop();
+    }
+    
+    public int top() {
+        return s1.peek();
+    }
+    
+    public int getMin() {
+        return s2.empty() ? -1 : s2.peek();
+    }
+}
 
+/**
+ * Your MinStack object will be instantiated and called as such:
+ * MinStack obj = new MinStack();
+ * obj.push(x);
+ * obj.pop();
+ * int param_3 = obj.top();
+ * int param_4 = obj.getMin();
+ */
 ```
 
 ### ...

lcci/03.02.Min Stack/README_EN.md

@@ -1,38 +1,117 @@
-# [03.02. Min Stack](https://leetcode-cn.com/problems/min-stack-lcci)
-
-## Description
-<p>How would you design a stack which, in addition to push and pop, has a function min which returns the minimum element? Push, pop and min should all operate in 0(1) time.</p>
-
-<p><strong>Example: </strong></p>
-
-<pre>
-MinStack minStack = new MinStack();
-minStack.push(-2);
-minStack.push(0);
-minStack.push(-3);
-minStack.getMin();   --&gt; return -3.
-minStack.pop();
-minStack.top();      --&gt; return 0.
-minStack.getMin();   --&gt; return -2.</pre>
-
-
-
-## Solutions
-
-
-### Python3
-
-```python
-
-```
-
-### Java
-
-```java
-
-```
-
-### ...
-```
-
-```
+# [03.02. Min Stack](https://leetcode-cn.com/problems/min-stack-lcci)
+
+## Description
+<p>How would you design a stack which, in addition to push and pop, has a function min which returns the minimum element? Push, pop and min should all operate in 0(1) time.</p>
+
+
+
+<p><strong>Example: </strong></p>
+
+
+
+<pre>
+
+MinStack minStack = new MinStack();
+
+minStack.push(-2);
+
+minStack.push(0);
+
+minStack.push(-3);
+
+minStack.getMin();   --&gt; return -3.
+
+minStack.pop();
+
+minStack.top();      --&gt; return 0.
+
+minStack.getMin();   --&gt; return -2.</pre>
+
+
+
+
+## Solutions
+
+
+### Python3
+
+```python
+class MinStack:
+
+    def __init__(self):
+        """
+        initialize your data structure here.
+        """
+        self._s1 = []
+        self._s2 = []
+
+
+    def push(self, x: int) -> None:
+        self._s1.append(x)
+        self._s2.append(x if len(self._s2) == 0 or self._s2[-1] >= x else self._s2[-1])
+
+    def pop(self) -> None:
+        self._s1.pop()
+        self._s2.pop()
+
+    def top(self) -> int:
+        return self._s1[-1]
+
+    def getMin(self) -> int:
+        return self._s2[-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()
+```
+
+### Java
+
+```java
+class MinStack {
+    private Stack<Integer> s1;
+    private Stack<Integer> s2;
+
+    /** initialize your data structure here. */
+    public MinStack() {
+        s1 = new Stack<>();
+        s2 = new Stack<>();
+    }
+    
+    public void push(int x) {
+        s1.push(x);
+        s2.push(s2.empty() || s2.peek() >= x ? x : s2.peek());
+    }
+    
+    public void pop() {
+        s1.pop();
+        s2.pop();
+    }
+    
+    public int top() {
+        return s1.peek();
+    }
+    
+    public int getMin() {
+        return s2.empty() ? -1 : s2.peek();
+    }
+}
+
+/**
+ * Your MinStack object will be instantiated and called as such:
+ * MinStack obj = new MinStack();
+ * obj.push(x);
+ * obj.pop();
+ * int param_3 = obj.top();
+ * int param_4 = obj.getMin();
+ */
+```
+
+### ...
+```
+
+```

lcci/03.02.Min Stack/Solution.java

@@ -0,0 +1,37 @@
+class MinStack {
+    private Stack<Integer> s1;
+    private Stack<Integer> s2;
+
+    /** initialize your data structure here. */
+    public MinStack() {
+        s1 = new Stack<>();
+        s2 = new Stack<>();
+    }
+    
+    public void push(int x) {
+        s1.push(x);
+        s2.push(s2.empty() || s2.peek() >= x ? x : s2.peek());
+    }
+    
+    public void pop() {
+        s1.pop();
+        s2.pop();
+    }
+    
+    public int top() {
+        return s1.peek();
+    }
+    
+    public int getMin() {
+        return s2.empty() ? -1 : s2.peek();
+    }
+}
+
+/**
+ * Your MinStack object will be instantiated and called as such:
+ * MinStack obj = new MinStack();
+ * obj.push(x);
+ * obj.pop();
+ * int param_3 = obj.top();
+ * int param_4 = obj.getMin();
+ */

lcci/03.02.Min Stack/Solution.py

@@ -0,0 +1,31 @@
+class MinStack:
+
+    def __init__(self):
+        """
+        initialize your data structure here.
+        """
+        self._s1 = []
+        self._s2 = []
+
+    def push(self, x: int) -> None:
+        self._s1.append(x)
+        self._s2.append(x if len(self._s2) ==
+                        0 or self._s2[-1] >= x else self._s2[-1])
+
+    def pop(self) -> None:
+        self._s1.pop()
+        self._s2.pop()
+
+    def top(self) -> int:
+        return self._s1[-1]
+
+    def getMin(self) -> int:
+        return self._s2[-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()