360 校招内存管理Java版

package Easy;

import java.util.Scanner;

public class Three2 {
public static void main(String[] args) {
Three2 t = new Three2();
Scanner in = new Scanner(System.in);
int T = in.nextInt();
int maxMem = in.nextInt();
int handleNum = 1;
Mem head = t.getMemInstance();
while(in.hasNext()){
String operation = in.next();
if(operation.equals("def")){
//整理内存不做任何输出
Mem p = head;
while(p.next!=null){
if(p.next.isDel){
p.next=p.next.next;
}else{
p=p.next;
}
}
}else if(operation.equals("new")){
//申请内存，成功返回句柄值，失败返回NULL
int size = in.nextInt();
Mem node = t.getMemInstance();
node.size = size;
Mem p = head;
Mem begin = head;
Mem end = head;
int totalUsed=0;
int innerCan = 0;
while(p!=null){
totalUsed += p.size;
if(p.isDel){
end = p;
innerCan += p.size;
}else{
begin = p;
innerCan = 0;
}
if(innerCan>=size){
end = end.next;
break;
}
if(p.next!=null){
p=p.next;
}else{
break;
}
}
if(innerCan>size){
Mem newNode1 = t.getMemInstance();
newNode1.size = size;
newNode1.handleNo = handleNum;
System.out.println(handleNum);
handleNum++;
Mem newNode2 = t.getMemInstance();
newNode2.size = innerCan-size;
newNode2.handleNo = -1;
newNode2.isDel = true;
newNode1.next = newNode2;
newNode2.next = end;
begin.next = newNode1;
}else if(innerCan==size){
Mem newNode = t.getMemInstance();
newNode.size = size;
newNode.handleNo = handleNum;
System.out.println(handleNum);
newNode.next=begin.next;
begin.next=newNode;
handleNum++;
}else if(maxMem-totalUsed>=size){
Mem newNode = t.getMemInstance();
newNode.size = size;
newNode.handleNo = handleNum;
System.out.println(handleNum);
handleNum++;
p.next=newNode;
}else{
System.out.println("NULL");
}
}else if(operation.equals("del")){
//释放句柄指向的内存，失败返回ILLEGAL_OPERATION，成功无输出
int index = in.nextInt();
Mem p = head;
boolean canDel = false;
if(index<handleNum){
while(p!=null){
if(p.handleNo==index){
if(!p.isDel){
p.isDel=true;
canDel = true;
}
break;
}
p=p.next;
}
}
if(!canDel){
System.out.println("ILLEGAL_OPERATION");
}
}
}
}

private Mem getMemInstance(){
return new Mem();
}

class Mem{
public int size=0;
public int handleNo=-1;
public Mem next = null;
public boolean isDel = false;
}
}