feat: add rust solution to lcof problem: No.30 (doocs#671)

面试题 30. 包含 min 函数的栈

Author: YangFong

lcof/面试题30. 包含min函数的栈/README.md

@@ -202,6 +202,66 @@ public:
 };
 ```
 
+### **Rust**
+
+```rust
+struct MinStack {
+    items: Vec<i32>,
+    min: Vec<i32>,
+}
+
+
+/**
+ * `&self` means the method takes an immutable reference.
+ * If you need a mutable reference, change it to `&mut self` instead.
+ */
+impl MinStack {
+
+    /** initialize your data structure here. */
+    fn new() -> Self {
+        MinStack {
+            items: Vec::new(),
+            min: Vec::new(),
+        }
+    }
+    
+    fn push(&mut self, x: i32) {
+        self.items.push(x);
+        match self.min.last() {
+            Some(min) => {
+                if *min >= x {
+                    self.min.push(x)
+                }
+            },
+            None => self.min.push(x)
+        }
+    }
+    
+    fn pop(&mut self) {
+        if self.items.pop().unwrap() == *self.min.last().unwrap() {
+            self.min.pop();
+        }
+    }
+    
+    fn top(&self) -> i32 {
+        *self.items.last().unwrap()
+    }
+    
+    fn min(&self) -> i32 {
+        *self.min.last().unwrap()
+    }
+}
+
+/**
+ * Your MinStack object will be instantiated and called as such:
+ * let obj = MinStack::new();
+ * obj.push(x);
+ * obj.pop();
+ * let ret_3: i32 = obj.top();
+ * let ret_4: i32 = obj.min();
+ */
+```
+
 ### **...**
 
 ```

lcof/面试题30. 包含min函数的栈/Solution.rs

@@ -0,0 +1,55 @@
+struct MinStack {
+    items: Vec<i32>,
+    min: Vec<i32>,
+}
+
+
+/**
+ * `&self` means the method takes an immutable reference.
+ * If you need a mutable reference, change it to `&mut self` instead.
+ */
+impl MinStack {
+
+    /** initialize your data structure here. */
+    fn new() -> Self {
+        MinStack {
+            items: Vec::new(),
+            min: Vec::new(),
+        }
+    }
+    
+    fn push(&mut self, x: i32) {
+        self.items.push(x);
+        match self.min.last() {
+            Some(min) => {
+                if *min >= x {
+                    self.min.push(x)
+                }
+            },
+            None => self.min.push(x)
+        }
+    }
+    
+    fn pop(&mut self) {
+        if self.items.pop().unwrap() == *self.min.last().unwrap() {
+            self.min.pop();
+        }
+    }
+    
+    fn top(&self) -> i32 {
+        *self.items.last().unwrap()
+    }
+    
+    fn min(&self) -> i32 {
+        *self.min.last().unwrap()
+    }
+}
+
+/**
+ * Your MinStack object will be instantiated and called as such:
+ * let obj = MinStack::new();
+ * obj.push(x);
+ * obj.pop();
+ * let ret_3: i32 = obj.top();
+ * let ret_4: i32 = obj.min();
+ */