hdu1702（ACboy needs your help again!） 在杭电又遇坑了

结题感悟：

栈：java.util 类 Stack<E>

Stack

[b]Stack()

boolean

empty()

E

peek()

E

pop()

E

push(E item)

int

search(Object o)

队列：java.util 接口 Queue<E>。这是一个接口不能直接使用，所以这里只能找它实现类ArrayDeque

ArrayDeque()

ArrayDeque(Collection<? extendsE> c)

ArrayDeque(int numElements)

void

addFirst(E e)

void

addLast(E e)

E

pop()

void

push(E e)

boolean

isEmpty()

Problem Description

Input

Output

Sample Input

4
4 FIFO
IN 1
IN 2
OUT
OUT
4 FILO
IN 1
IN 2
OUT
OUT
5 FIFO
IN 1
IN 2
OUT
OUT
OUT
5 FILO
IN 1
IN 2
OUT
IN 3
OUT

Sample Output

1
2
2
1
1
2
None
2
3

直接用java包中的类：

package stack;

import java.util.ArrayDeque;
import java.util.Scanner;
import java.util.Stack;

public class P1702_2 {

	public staticvoid main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int t = sc.nextInt();
		String mode, operate;
		int num, a;
		while (t-- > 0) {
			int n = sc.nextInt();
			mode = sc.next();
			if (mode.charAt(2) == 'F') {
				ArrayDeque queue=new ArrayDeque(n);
				for (int i = 0; i < n; i++) {
					operate = sc.next();
					if (operate.charAt(0) == 'I') {
						num = sc.nextInt();
						queue.addLast(num);
					} else {
						if (queue.isEmpty()) {
							System.out.println("None");
						} else {
							System.out.println(queue.pop());
						}
					}
				}
			} else {
				Stack stack = new Stack();
				for (int i = 0; i < n; i++) {
					operate = sc.next();
					if (operate.charAt(0) == 'I') {
						num = sc.nextInt();
						stack.push(num);
					} else {
						if (stack.isEmpty()) {
							System.out.println("None");
						} else {
							System.out.println(stack.pop());
						}
					}
				}
			}
		}
	}
}

自己写的类（数据都能过，就是不能ac）：

package stack;

import java.util.Scanner;

public class P1702 {

	public staticvoid main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int t = sc.nextInt();
		String mode, operate;
		int num, a;
		while (t-- > 0) {
			int n = sc.nextInt();
			mode = sc.next();
			if (mode.charAt(2) == 'F') {
				Queue queue = new Queue(n);
				for (int i = 0; i < n; i++) {
					operate = sc.next();
					if (operate.charAt(0) == 'I') {
						num = sc.nextInt();
						queue.add(num);
					} else {
						a = queue.pop();
						if (a == 0) {
							System.out.println("None");
						} else {
							System.out.println(a);
						}
					}
				}
			} else {
				Stacks stack = new Stacks(n);
				for (int i = 0; i < n; i++) {
					operate = sc.next();
					if (operate.charAt(0) == 'I') {
						num = sc.nextInt();
						stack.inStack(num);
					} else {
						a = stack.outStack();
						if (a == 0) {
							System.out.println("None");
						} else {
							System.out.println(a);
						}
					}
				}
			}
		}
	}
}

class Queue {

	int end;
	finalint FRONT = 0;
	int[] queue;

	public Queue(int n) {
		end = 0;
		queue = newint[n+10];
	}

	publicvoid add(int p) {// 入队
		queue[end++] = p;
	}

	publicint pop() {// 出队
		if (end <= 0) {
			return 0;
		}
		int p = queue[FRONT];
		if (end > 1) {// 队首出队，则后面的要补上来
			for (int i = 0; i < end; i++) {
				queue[i] = queue[i + 1];
			}
		}
		end--;
		return p;
	}

}

class Stacks {
	int top;
	int[] stack;

	public Stacks(int n) {
		top=0;
		stack = newint
;
	}

	publicvoid inStack(int p) {
		stack[top++] = p;
	}

	publicint outStack() {
		if (top==0) {
			return 0;
		}
		return stack[--top];
	}

}