数据结构--栈

 

1，栈先进后出

2,   java版栈操作

3，中间不能插入数据

public class MyStack {
    //栈的底层用数组来存储数据，每次压入数据在数据最底，
    int[] elements;

    public MyStack() {
        elements = new int[0];
    }
    //压入元素
    public void push(int element) {
        int[] newArr = new int[elements.length + 1];
        for (int i = 0; i < elements.length; i++) {
            newArr[i] = elements[i];
        }
        newArr[elements.length] = element;
        elements = newArr;
    }
    //取出栈顶元素
    public int pop(){
        if(elements.length==0){
            throw new RuntimeException("stack is empty");
        }
        int element=elements[elements.length-1];
        int[] newArr=new int[elements.length-1];
        for(int i=0;i<elements.length-1;i++){
            newArr[i]=elements[i];
        }
        elements=newArr;
        return element;
    }
    //查看栈顶
    public int peek(){
        return elements[elements.length-1];
    }

}