import java.util.Scanner;
public class A {
final static int M=4; //进程数
final static int N=3; //资源种类数
static int available[]={0,0,0}; //各进程可利用的资源情况
static int max[][]={{0,0,0},{0,0,0},{0,0,0},{0,0,0}}; //各进程最大需求的资源情况
static int allocation[][]={{0,0,0},{0,0,0},{0,0,0},{0,0,0}}; //各进程已经分配的资源情况
static int need[][]={{0,0,0},{0,0,0},{0,0,0},{0,0,0}}; //各进程仍需要的资源情况
static int request[]={0,0,0};
public static void main(String[] args) {
Scanner in=new Scanner(System.in);
int m=0,n=0,i=0,j=0;
System.out.print(" 死锁的检测与解除 ");
input();
output();
enter1(n);
enter2(n,j);
System.out.println();
change(n);
if(checksafe(n)==1)
{
check(m,n,i,j);
output();
}
}
static void enter2(int n,int j){
Scanner in=new Scanner(System.in);
System.out.printf("请输入进程%d对3类资源的需求量:",n);
for(j=0;j<3;j++)
{
request[j]=in.nextInt();
if(request[j]>need[n][j])
{
System.out.println("申请的资源数量大于自身需求的最大值！请重新输入！");
enter2(n,j);
}
else
{
if(request[j]>available[j])
{
System.out.println("申请的资源数量大于可用的资源数量！请重新输入！");
enter2(n,j);
}
}
}
}
static void enter1(int n){
Scanner in=new Scanner(System.in);
System.out.print("请输入请求资源的进程号:");
n=in.nextInt();
if(n<0||n>=M)
{
System.out.printf("您输入的进程号不存在，请重新输入！\n");
enter1(n);
}
}
static void check(int m,int n,int i,int j){
m=findmany();
System.out.println();
System.out.printf("撤销进程%d所占用的资源！\n",m);
for(j=0;j<3;j++)
{
available[j]+=allocation[m][j];
need[m][j]+=allocation[m][j];
allocation[m][j]=0;
}
n=findfew();
for(j=0;j<3;j++)
{
request[j]=need[n][j];
}
change(n);
if(checksafe(n)==1) check(m,n,i,j);
}
static void input()
{
Scanner in=new Scanner(System.in);
int i=0,j=0;
System.out.println("\t\t\t\tA B C");
System.out.printf("请输入进程0对3类资源的最大需求:");
for(j=0;j<3;j++)
{
max[0][j]=in.nextInt();
}
System.out.printf("请输入进程1对3类资源的最大需求:");
for(j=0;j<3;j++)
{
max[1][j]=in.nextInt();
}
System.out.printf("请输入进程2对3类资源的最大需求:");
for(j=0;j<3;j++)
{
max[2][j]=in.nextInt();
}
System.out.printf("请输入进程3对3类资源的最大需求:");
for(j=0;j<3;j++)
{
max[3][j]=in.nextInt();
}
System.out.printf("请输入进程0已分配的3类资源量:");
for(j=0;j<3;j++)
{
allocation[0][j]=in.nextInt();
}
System.out.printf("请输入进程1已分配的3类资源量:");
for(j=0;j<3;j++)
{
allocation[1][j]=in.nextInt();
}
System.out.printf("请输入进程2已分配的3类资源量:");
for(j=0;j<3;j++)
{
allocation[2][j]=in.nextInt();
}
System.out.printf("请输入进程3已分配的3类资源量:");
for(j=0;j<3;j++)
{
allocation[3][j]=in.nextInt();
}
System.out.printf("请输入可利用的3类资源量:");
for(j=0;j<3;j++)
{
available[j]=in.nextInt();
}
for(i=0;i<4;i++)
for(j=0;j<3;j++)
{
need[i][j]=max[i][j]-allocation[i][j];
}
System.out.println();
}
/***************显示当前的资源状况***************/
static void output()
{
int i=0,j=0;
System.out.printf("该时刻3类资源的分配情况如下:\n");
System.out.printf("\tMAX\t\tALOCAT\t\tNEED\t\tAVAILABLE\n");
System.out.printf("进程0:\t");
for(j=0;j<3;j++)
{
System.out.printf("%d ",max[0][j]);
}
System.out.printf("\t");
for(j=0;j<3;j++)
{
System.out.printf("%d ",allocation[0][j]);
}
System.out.printf("\t");
for(j=0;j<3;j++)
{
System.out.printf("%d ",need[0][j]);
}
System.out.printf("\t");
for(j=0;j<3;j++)
{
System.out.printf("%d ",available[j]);
}
System.out.println();
System.out.printf("进程1:\t");
for(j=0;j<3;j++)
{
System.out.printf("%d ",max[1][j]);
}
System.out.printf("\t");
for(j=0;j<3;j++)
{
System.out.printf("%d ",allocation[1][j]);
}
System.out.printf("\t");
for(j=0;j<3;j++)
{
System.out.printf("%d ",need[1][j]);
}
System.out.printf("\n");
System.out.printf("进程2:\t");
for(j=0;j<3;j++)
{
System.out.printf("%d ",max[2][j]);
}
System.out.printf("\t");
for(j=0;j<3;j++)
{
System.out.printf("%d ",allocation[2][j]);
}
System.out.printf("\t");
for(j=0;j<3;j++)
{
System.out.printf("%d ",need[2][j]);
}
System.out.printf("\n");
System.out.printf("进程3:\t");
for(j=0;j<3;j++)
{
System.out.printf("%d ",max[3][j]);
}
System.out.printf("\t");
for(j=0;j<3;j++)
{
System.out.printf("%d ",allocation[3][j]);
}
System.out.printf("\t");
for(j=0;j<3;j++)
{
System.out.printf("%d ",need[3][j]);
}
System.out.printf("\n");
}
/***************给某进程分配资源***************/
static void change(int n)
{
int j;
for(j=0;j<N;j++)
{
available[j]=available[j]-request[j];
allocation[n][j]=allocation[n][j]+request[j];
need[n][j]=need[n][j]-request[j];
}
}
/***************找出占用资源最多的进程***************/
static int findmany()
{
int i=0,j=0,k=0,l=0;
i=allocation[0][0]+allocation[0][1];
i+=allocation[0][2];
j=allocation[1][0]+allocation[1][1];
j+=allocation[1][2];
k=allocation[2][0]+allocation[2][1];
k+=allocation[2][2];
l=allocation[3][0]+allocation[3][1];
l+=allocation[3][2];
if(i>=j)
{
if(i>=k)
{
if(i>=l)
return 0;
else
return 3;
}
else
{
if(k>=l)
return 2;
else
return 3;
}
}
else
{
if(j>=k)
{
if(j>=l)
return 1;
else
return 3;
}
else
{
if(k>=l)
return 2;
else
return 3;
}
}
}
/***************找出需要资源最少的进程***************/
static int findfew()
{
int i=0,j=0,k=0,l=0;
i=need[0][0]+need[0][1];
i+=need[0][2];
j=need[1][0]+need[1][1];
j+=need[1][2];
k=need[2][0]+need[2][1];
k+=need[2][2];
l=need[3][0]+need[3][1];
l+=need[3][2];
if(i<=j)
{
if(i<=k)
{
if(i<=l)
return 0;
else
return 3;
}
else
{
if(k<=l)
return 2;
else
return 3;
}
}
else
{
if(j<=k)
{
if(j<=l)
return 1;
else
return 3;
}
else
{
if(k<=l)
return 2;
else
return 3;
}
}
}
/***************安全性检测***************/
static int checksafe(int n)
{
int work[]=new int[3],finish[]=new int[M],que[]=new int[M];
int i=0,k=0;
for(i=0;i<M;i++)
finish[i]=0;
for(;;)
{
work[0]=available[0];
work[1]=available[1];
work[2]=available[2];
i=n;
while(i<M)
{
if(finish[i]==0&&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];
finish[i]=1;
que[k]=i;
k++;
i=0;
}
else
i++;
}
for(i=0;i<M;i++)
if(finish[i]==0)
{
System.out.printf("存在死锁！\n");
return 1;
}
break;
}
System.out.printf("\n");
System.out.printf("检测结果:不存在死锁！\n");
System.out.printf("安全序列为:");
for(i=0;i<M;i++)
System.out.printf("%d\t\t",que[i]);
System.out.println();
output();
return 0;
}
}
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