360 校招内存管理Java版

来源：互联网发布：adc0804 51单片机编辑：程序博客网时间：2024/05/20 21:44
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;    }}
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