MinStack C++

minstack.cpp

// Leetcode https://leetcode.com/problems/min-stack
// What's a min stack? A min stack is a stack (first in, last out) that also tracks the minimum value at any given point of time.
// push, pop, top and min element need to be constant time.

class StackNode{
    public:
    int val;
    int minval;
    
    StackNode(int x, int min): val(x), minval(min) {};
    
};

class MinStack {
public:
    /** initialize your data structure here. */
    
    stack<StackNode> customstack;
    int minval;
    
    MinStack() {
        minval = INT_MAX;
    }
    
    void push(int x) {
        StackNode node(x, minval);
        customstack.push(node);
        if(x < minval) minval = x;
    }
    
    void pop() {
        StackNode tops = customstack.top();
        if(tops.val == minval) minval = tops.minval;
        
        customstack.pop();
    }
    
    int top() {
        StackNode tops = customstack.top();
        return tops.val;
    }
    
    int getMin() {
        return minval;
    }
};

/**
 * 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();
 */