[LeetCode] - M - Min Stack

https://leetcode.com/problems/min-stack/description/?envType=study-plan-v2&envId=top-interview-150 

Min Stack - LeetCode

 

📌 - 풀이

1. stack 2개를 만들어서 하나를 min stack으로

2. push할 때, val 값이 min의 peek()보다 작으면 min stack에 푸쉬

3. pop할 때, stack과 min의 peek()가 같으면 min도 pop

 

 

🔥 - Java 코드

 

class MinStack {
    Stack<Integer> stack;
    Stack<Integer> min;
    public MinStack() {
        stack = new Stack<>();
        min = new Stack<>();
    }
    
    public void push(int val) {
        stack.push(val);
        if(min.isEmpty() || min.peek() >= val){
            min.push(val);
        }
        
    }
    
    public void pop() {
        if(stack.pop().equals(min.peek())){
            min.pop();
        }
        
    }
    
    public int top() {
        return stack.peek();
    }
    
    public int getMin() {
        return min.peek();
    }
}

/**
 * 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();
 */