os

/*
 * slj
 * 2016-12-13
 */
import java.util.Scanner;

public class simpleBanker {
    //进程数
    private int number = 5;
    //资源数
    private int number2 = 3;
    //可得到的资源
    private int available[] = new int[]{3,3,2};
    //进程名字
    private String[] name = new String[]{"P1","P2","P3","P4","P5","P6"};
    //每个进程最大资源数
    private int max[][] = new int[][]{{7,5,3},{3,2,2},{9,0,2},{2,2,2},{4,3,3}};
    //每个进程目前拥有的资源数
    private int allocation[][] = new int[][]{{0,1,0},{2,0,0},{3,0,2},{2,1,1},{0,0,2}};
    //每个进程需要的资源数
    private int need[][] = new int[number][number2];

    //初始输入
    private void showBegin(){
        System.out.println("初始数据：");
        System.out.println("进程号\tMax\t    Allocation\tAvailabel\t");
        System.out.println("\tA  B  C\t    A  B  C\tA  B  C");
        for(int i = 0;i<number;i++) {
            System.out.print(name[i] + "\t");
            for(int m = 0;m<3;m++) System.out.print(max[i][m]+"  ");
            System.out.print("   ");
            for(int m = 0;m<3;m++) System.out.print(allocation[i][m]+"  ");
            System.out.print("\t");
            if(i==0){
                for(int m = 0;m<3;m++) System.out.print(available[m]+"  ");
                System.out.print("\t");
            }
            System.out.println();
        }
        //需要资源情况
        for(int i= 0;i<number;i++){
            for(int j=0;j<number2;j++){
                need[i][j] = max[i][j] - allocation[i][j];
            }
        }
        System.out.println("每个进程请求资源：");
        System.out.println("进程号\tNeed");
        System.out.println("\tA  B  C");
        for(int i = 0;i<number;i++) {
            System.out.print(name[i] + "\t");
            for(int m = 0;m<3;m++) System.out.print(need[i][m]+"  ");
            System.out.println();
        }
    }
    
    //寻找所有安全序列
    int sum = 0;
    int tmp = 0;
    String str = "";
    int[] work = available;
    boolean[] flag = new boolean[number];
    private void find(){
        if(tmp == number){
            System.out.println(str);
            sum++;
            return ;
        }
        else{
            for(int i=0;i<number;i++){
                if((flag[i] == false)&&(need[i][0]<=work[0])&&(need[i][1]<=work[1])&&(need[i][2]<=work[2])){
                    work[0]+=allocation[i][0];
                    work[1]+=allocation[i][1];
                    work[2]+=allocation[i][2];
                    flag[i]=true;
                    tmp++;
                    str+=name[i]+" ";
                    find();
                    str=str.substring(0,str.length()-3);
                    tmp--;
                    flag[i]=false;
                    work[0]-=allocation[i][0];
                    work[1]-=allocation[i][1];
                    work[2]-=allocation[i][2];
                }
            }
        }
    }
    
    //资源请求
    boolean change(int inRequestNum,int inRequest[]){
        int requestNum = inRequestNum;
        int request[] = inRequest;
        if(!(request[0]<=need[requestNum][0]&&request[1]<=need[requestNum][1]&&request[2]<=need[requestNum][2]))
        {
            System.out.println("请求的资源数超过了所需要的最大值，分配错误");
            return false;
        }
        if((request[0]<=available[0]&&request[1]<=available[1]&&request[2]<=available[2])==false){
            System.out.println("尚无足够资源分配，必须等待");
            return false;
        }
        for(int i = 0;i<3;i++){
            available[i] = available[i]-request[i];
            allocation[requestNum][i] = allocation[requestNum][i] + request[i];
            need[requestNum][i] = need[requestNum][i] - request[i];
        }
        sum = 0;
        tmp = 0;
        str = "";
        work = available;
        flag = new boolean[number];
        find();//进行安全性检查并返回是否安全
        // System.out.println("安全性检查后"+flag);
        if(sum > 0) {
            System.out.println("能够安全分配");
            return true;
        }
        else//不能通过安全性检查 恢复到未分配前的数据
        {
        System.out.println("不能够安全分配");
        for(int i = 0;i<3;i++){
            available[i] = available[i]+request[i];
            allocation[requestNum][i] = allocation[requestNum][i] - request[i];
            need[requestNum][i] = need[requestNum][i] + request[i];
            }
        return false;
        }

    }


    public void Test(){
        showBegin();    
        //寻找所以安全序列
        System.out.println("有如下安全序列：");
        sum=0;
        find();
        System.out.println("一共有" + sum + "个安全序列。");
        
        int request[] =new int[3];
        int requestNum;
        String source[] = new String[]{"A","B","C"};
        Scanner s = new Scanner(System.in);
        String choice = new String();
        while(true){
            System.out.println("请输入要请求的进程号（0--4）：");
            requestNum = s.nextInt();
            System.out.print("请输入请求的资源数目");
            for(int i = 0;i<3;i++){
                System.out.println(source[i]+"资源的数目：");
                request[i] = s.nextInt();
            }
            change(requestNum, request);
            System.out.println("是否再请求分配(y/n)");
            choice = s.next();
            if(choice.equals("n"))
                break;
        }
        return ;
    }
}