题解 | #【模板】栈#
【模板】栈
http://www.nowcoder.com/practice/104ce248c2f04cfb986b92d0548cccbf
import java.util.Scanner;
//使用一个数组作为栈，初始容量为10
//使用一个int成员变量作为指针，指向栈顶。
//push前先判断栈是否满，若满了，则扩容两倍。
public class Main{
public static void main(String[] args){
MyStack stack = new MyStack();
Scanner scanner = new Scanner(System.in);
int optNum = scanner.nextInt();
String line = scanner.nextLine();
while(optNum>0){
line = scanner.nextLine();
if(line.length()>3){
line = line.substring(5);
stack.push(Integer.parseInt(line));
}else{
if(line.charAt(0) == 't'){
stack.top();
}else{
stack.pop();
}
}
optNum--;
}
}
}
class MyStack{
int arr[];
int index;
public MyStack(){
arr = new int[10];
index = 0;
}
public void push(int x){
extend();
arr[index++] = x;
}
public void pop(){
if(index == 0){
System.out.println("error");
}else{
System.out.println("" + arr[--index]);
}
}
public void top(){
if(index == 0){
System.out.println("error");
}else{
System.out.println("" + arr[index-1]);
}
}
public void extend(){
if(index == arr.length-1){
int[] temp = new int[arr.length*2];
for(int i = 0; i < arr.length; i++){
temp[i] = arr[i];
}
arr = temp;
}
}
}
