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MyStack.java
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MyStack.java
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public class MyStack {
//栈的底层我们使用数组存放数据
int[] elements;
public MyStack(){
elements = new int[0];
}
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(){
//取出数组的最后一个元素
//栈中没有元素的判定
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<newArr.length;i++){
newArr[i]=elements[i];
}
elements=newArr;
return element;
}
public int peek(){
if(elements.length==0){
throw new RuntimeException("Stack is empty");
}
return elements[elements.length-1];
}
public boolean isEmpty(){
return (elements.length==0);
}
}