impl Min Stack

leetcode-cc/MinStack.hpp

@@ -1,3 +1,7 @@
+#include <algorithm>
+#include <climits>
+#include <stack>
+
 #include "TestHelper.h"
 #include "problem.h"
 #include "solution.h"
@@ -8,7 +12,7 @@ IMPLEMENT_PROBLEM_CLASS(PMinStack, 155, DIFFI_MEDIUM, TOPIC_ALGORITHMS,
                         "Min Stack",
                         "Design a stack that supports push, pop, top, and "
                         "retrieving the minimum element in constant time.",
-                        {""});
+                        {"Stack"});
 
 class SMinStack : public ISolution {
  public:
@@ -23,14 +27,24 @@ class SMinStack : public ISolution {
  private:
   class MinStack {
    public:
-    MinStack() {}
+    MinStack() {
+      s = {};
+      s.push({0, INT_MAX});
+    }
+
+    void push(int val) {
+      int preMin = this->s.top().second;
+      auto element = make_pair(val, min(val, preMin));
+      this->s.push(element);
+    }
 
-    void push(int val) {}
+    void pop() { this->s.pop(); }
 
-    void pop() {}
+    int top() { return this->s.top().first; }
 
-    int top() {}
+    int getMin() { return this->s.top().second; }
 
-    int getMin() {}
+   private:
+    stack<pair<int, int>> s;
   };
 };