minstack.cpp

class MinStack {
public:
 stack <int> box;
 int min1 = INT32_MAX;
 void push(int x) {
 if(x<=min1)
 {
 box.push(min1);
 min1 = x;
 }
 box.push(x);
 }

 void pop() {
 int up = box.top();

 box.pop();
 if(up==min1)
 {
 min1 = box.top();
 box.pop();
 }
 }

 int top() {
 return box.top();
 }

 int getMin() {
 return min1;
 }
};

/**
 * 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();
 */