【一刷《剑指Offer》】面试题 21：包含 main 函数的栈

//力扣
class MinStack {
private:
    stack<int> val_stack;
    stack<int> min_stack;
public:
    MinStack() {}
    
    void push(int val) {
        val_stack.push(val);
        if(min_stack.empty() || val<min_stack.top())
            min_stack.push(val);
        else
            min_stack.push(min_stack.top());
    }
    
    void pop() {
        if(val_stack.empty() || min_stack.empty()) return;
        val_stack.pop();
        min_stack.pop();
    }
    
    int top() {
        return val_stack.top();
    }
    
    int getMin() {
        return min_stack.top();
    }
};
 
/**
 * Your MinStack object will be instantiated and called as such:
 * MinStack* obj = new MinStack();
 * obj->push(val);
 * obj->pop();
 * int param_3 = obj->top();
 * int param_4 = obj->getMin();
 */
 
//牛客
class Solution {
private:
    stack<int> val_stack;
    stack<int> min_stack;
public:
    void push(int value) {
        val_stack.push(value);
        if(min_stack.empty() || value<min_stack.top())
            min_stack.push(value);
        else
            min_stack.push(min_stack.top());
    }
    void pop() {
        val_stack.pop();
        min_stack.pop();
    }
    int top() {
        return val_stack.top();
    }
    int min() {
        return min_stack.top();
    }
};