银行家算法 C语言实现

关于银行家算法就不赘述了，首先是结果截图：

下面是代码：

#include 
#include 
#include 

#define TRUE 1
#define FALSE 0

int N_resource, N_process;	// 资源数和进程数
// 银行家算法用到的数据结构
int *Avaliable = NULL;
int **Max = NULL;
int **Allocation = NULL;
int **Need = NULL;
int requestID = 0;	// 申请资源的进程ID
int *Request = NULL;

// 输入向量和矩阵
void input(FILE *fp) {
	char buf[100];
	// 输入N_resource and N_process
	fgets(buf, 100, fp);
	N_resource = atoi(strtok(buf, " "));
	N_process = atoi(strtok(NULL, " "));
	printf("%d resource %d processn", N_resource, N_process);
	// 输入Avaliable向量
	Avaliable = (int *)malloc(sizeof(int) * N_resource);
	fgets(buf, 100, fp);
	Avaliable[0] = atoi(strtok(buf, " "));
	for (int i = 1; i < N_resource; i++) {
		Avaliable[i] = atoi(strtok(NULL, " "));
	}
	// 输入Max矩阵
	Max = (int **)malloc(sizeof(int *) * N_process);
	fgets(buf, 100, fp);	// 跳过空行
	for (int i = 0; i < N_process; i++) {
		Max[i] = (int *)malloc(sizeof(int) * N_resource);
		
		fgets(buf, 100, fp);
		Max[i][0] = atoi(strtok(buf, " "));
		for (int j = 1; j < N_resource; j++) {
			Max[i][j] = atoi(strtok(NULL, " "));
		}
	}
	// 输入Allocation矩阵
	Allocation = (int **)malloc(sizeof(int *) * N_process);
	fgets(buf, 100, fp);	// 跳过空行
	for (int i = 0; i < N_process; i++) {
		Allocation[i] = (int *)malloc(sizeof(int) * N_resource);
	
		fgets(buf, 100, fp);
		Allocation[i][0] = atoi(strtok(buf, " "));
		for (int j = 1; j < N_resource; j++) {
			Allocation[i][j] = atoi(strtok(NULL, " "));
		}
	}
	// 初始化Need矩阵
	Need = (int **)malloc(sizeof(int *) * N_process);
	for (int i = 0; i < N_process; i++) {
		Need[i] = (int *)malloc(sizeof(int) * N_resource);
		for (int j = 0; j < N_resource; j++)
			Need[i][j] = Max[i][j] - Allocation[i][j];
	}
	// 输入requestID
	fgets(buf, 100, fp);	// 跳过空行
	fgets(buf, 100, fp);
	requestID = atoi(buf);
	// 输入Request向量
	Request = (int *)malloc(sizeof(int) * N_resource);
	fgets(buf, 100, fp);
	Request[0] = atoi(strtok(buf, " "));
	for (int i = 1; i < N_resource; i++) {
		Request[i] = atoi(strtok(NULL, " "));
	}
}

// 打印当前状态
void print_state() {
	printf("Avaliable: ");
	for (int i = 0; i < N_resource; i++)
		printf("%d ", Avaliable[i]);
	printf("n");
	printf("processIdtMaxttAllocationtNeedn");
	for (int i = 0; i < N_process; i++) {
		printf("    %dtt", i);
		for (int j = 0; j < N_resource; j++)
			printf("%d ", Max[i][j]);
		printf("t");
		for (int j = 0; j < N_resource; j++)
			printf("%d ", Allocation[i][j]);
		printf("t");
		for (int j = 0; j < N_resource; j++)
			printf("%d ", Need[i][j]);
		printf("n");
	}
}

// 判断是否所有的arrayA[i] <= arrayB[i]
int ALessthanB(int *arrayA, int *arrayB, int N) {
	for (int i = 0; i < N; i++)
		if (arrayA[i] > arrayB[i])
			return FALSE;
	return TRUE;
}

// 判断当前是否是安全状态
int isSafety() {
	int *Work = malloc(sizeof(int) * N_resource);
	int *Finish = malloc(sizeof(int) * N_process);
	for (int i = 0; i < N_resource; i++)
		Work[i] = Avaliable[i];
	for (int i = 0; i < N_process; i++)
		Finish[i] = FALSE;
	
	printf("The allocation sequence is:n");
	printf("allocate totNow Avaliablen");
	for (int i = 0; i < N_process; i++) {
		if (Finish[i] == TRUE)
			continue;
		int findit = FALSE;
		for (int j = 0; j < N_resource; j++) {
			// 对于该进程i，判断是否所有资源Need[i][j] <= Work[j]
			if (ALessthanB(Need[i], Work, N_resource)) {
				findit = TRUE;
				break;
			}
		}
		if (findit) {
			for (int j = 0; j < N_resource; j++)
				Work[j] += Allocation[i][j];
			Finish[i] = TRUE;
			// 打印安全序列的判断路径
			printf("process %dt", i);
			for (int j = 0; j < N_resource; j++)
				printf("%d ", Work[j]);
			printf("n");
			// 重新搜索
			i = -1;
		}
	}
	free(Work);
	// 判断是否所有的Finish[i]都是TRUE
	for (int i = 0; i < N_process; i++) {
		if (Finish[i] == FALSE) {
			free(Finish);
			return FALSE;
		}
	}
	free(Finish);
	return TRUE;
}

// int ID，是申请资源的进程ID
// 判断是否允许该进程的申请
int allowRequest(int ID) {
	// print the Request array
	printf("RequestID: %dtRequest: ", requestID);
	for (int i = 0; i < N_resource; i++)
		printf("%d ", Request[i]);
	printf("n");
	
	if (!ALessthanB(Request, Need[ID], N_resource)) {
		printf("Error: Request <= Needn");
		return FALSE;
	}
	if (!ALessthanB(Request, Avaliable, N_resource)) {
		printf("Error: Request <= Avaliablen");
		return FALSE;
	}
	
	// 尝试分配申请的资源
	for (int i = 0; i < N_resource; i++) {
		Avaliable[i] -= Request[i];
		Allocation[ID][i] += Request[i];
		Need[ID][i] -= Request[i];
	}
	printf("now try to allocate the Requested resourcen");
	print_state();
	
	if (isSafety())
		return TRUE;
	else {
		// 不能允许该申请，恢复原先的数据结构
		for (int i = 0; i < N_resource; i++) {
			Avaliable[i] += Request[i];
			Allocation[ID][i] -= Request[i];
			Need[ID][i] += Request[i];
		}
		return FALSE;
	}
}


int main(int argc, char *argv[]) {
	FILE *fp = NULL;
	if ((fp = fopen(argv[1], "r")) == NULL) {
		printf("%s: No such file or directoryn", argv[1]);
		return 0;
	}
	input(fp);
	printf("The inisialized state is:n");
	print_state();
	
	printf("Judge whether the inisialized state is safety:n");
	if (isSafety())
		printf("The inisialized state is safetynn");
	else
		printf("The inisialized state is unsafetynn");
	
	printf("Judge should we allocate resource to process%dn", requestID);
	if (allowRequest(requestID))
		printf("This request is safetyn");
	else
		printf("This request is unsafetyn");
	
	// 释放内存
	for (int i = 0; i < N_process; i++) {
		free(Max[i]);	free(Allocation[i]);	free(Need[i]);
	}
	free(Avaliable);	free(Max);
	free(Allocation);	free(Need);
	return 0;
}

测试用例是：

4 5
1 6 2 2

0 0 4 4
2 7 5 0
3 6 10 10
0 9 8 4
0 6 6 10

0 0 3 2
1 0 0 0
1 3 5 4
0 3 3 2
0 0 1 4

2
1 3 1 0