🌗 剑指 Offer 30. 包含min函数的栈

难度: 🌗

问题描述

---

解法

class MinStack {
    // 思路：
    // 借助 辅助栈，存放最小值
    LinkedList<Integer> stack;
    LinkedList<Integer> ts;

    /** initialize your data structure here. */
    public MinStack() {
        stack = new LinkedList<>();
        ts = new LinkedList<>();
    }
    
    public void push(int x) {
        stack.push(x);
        if(ts.isEmpty() || x <= ts.peek()) {
            ts.push(x);
        }
    }
    
    public void pop() {
        int val = stack.pop();
        if(!ts.isEmpty() && val == ts.peek()) {
            ts.pop();
        }
    }
    
    public int top() {
        return stack.peek();
    }
    
    public int min() {
        return ts.peek();
    }
}

/**
 * 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.min();
 */

---

输出