Add solution 0155 in cpp

Author: KongJHong

solution/0155.Min Stack/Solution.cpp

@@ -0,0 +1,40 @@
+class MinStack {//方法1
+public:
+    /** initialize your data structure here. */
+    stack<int> s;
+    MinStack() {
+        
+    }
+    
+    void push(int x) {
+        if(s.empty()) {
+            s.push(x);
+            s.push(x);
+        } else {
+            int temp = s.top();
+            s.push(x);
+            if(x < temp) {
+                s.push(x);
+            } else {
+                s.push(temp);
+            }
+        }
+    }
+    
+    void pop() {
+        s.pop();
+        s.pop();
+    }
+    
+    int top() {
+        int temp = s.top();
+        s.pop();
+        int top = s.top();
+        s.push(temp);
+        return top;
+    }
+    
+    int getMin() {
+        return s.top();
+    }
+};