Banker_Algorithm_Greedy_Approach.cpp

Greedy Algorithms/Banker_Algorithm_Greedy_Approach.cpp

@@ -0,0 +1,176 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+void final_output(int k[][10], int n, int p)
+{
+	int i, j;
+	for (i = 0; i < n; i++)
+	{
+		printf("\n");
+		for (j = 0; j < p; j++)
+		{
+			printf("%d\t", k[i][j]);
+		}
+	}
+}
+
+void Banker(int A[][10], int N[][10],
+	int M[10][10], int W[1][10], int *n, int *m)
+{
+	int i, j;
+	printf("\n Enter total number of processes : ");
+	scanf("%d", n);
+	printf("\n Enter total number of resources : ");
+	scanf("%d", m);
+	for (i = 0; i<*n; i++)
+	{
+		printf("\n Process %d\n", i + 1);
+		for (j = 0; j<*m; j++)
+		{
+			printf(" Allocation for resource %d : ", j + 1);
+			scanf("%d", &A[i][j]);
+			printf(" Maximum for resource %d : ", j + 1);
+			scanf("%d", &M[i][j]);
+		}
+	}
+
+	printf("\n Available resources : \n");
+	for (i = 0; i<*m; i++)
+	{
+		printf(" Resource %d : ", i + 1);
+		scanf("%d", &W[0][i]);
+	}
+
+	for (i = 0; i<*n; i++)
+		for (j = 0; j<*m; j++)
+			N[i][j] = M[i][j] - A[i][j];
+	printf("\n -----Allocation Matrix-----");
+	final_output(A, *n, *m);
+	printf("\n -----Maximum Requirement Matrix-----");
+	final_output(M, *n, *m);
+	printf("\n -----Need Matrix-----");
+	final_output(N, *n, *m);
+}
+
+int safety(int A[][10], int N[][10],
+	int B[1][10], int n, int m, int a[])
+{
+	int i, j, k, x = 0, f1 = 0, f2 = 0;
+	int F[10], W[1][10];
+	for (i = 0; i < n; i++)
+		F[i] = 0;
+	for (i = 0; i < m; i++)
+		W[0][i] = B[0][i];
+	for (k = 0; k < n; k++)
+	{
+		for (i = 0; i < n; i++)
+		{
+			if (F[i] == 0)
+			{
+				f2 = 0;
+				for (j = 0; j < m; j++)
+				{
+					if (N[i][j] > W[0][j])
+						f2 = 1;
+				}
+
+				if (f2 == 0 && F[i] == 0)
+				{
+					for (j = 0; j < m; j++)
+						W[0][j] += A[i][j];
+					F[i] = 1;
+					f1++;
+					a[x++] = i;
+				}
+			}
+		}
+
+		if (f1 == n)
+			return 1;
+	}
+
+	return 0;
+}
+
+void request(int A[10][10], int N[10][10], int B[10][10], int pid, int K)
+{
+	int rmat[1][10];
+	int i;
+	printf("\n Enter additional request : \n");
+	for (i = 0; i < K; i++)
+	{
+		printf(" Request for resource %d : ", i + 1);
+		scanf("%d", &rmat[0][i]);
+	}
+
+	for (i = 0; i < K; i++)
+		if (rmat[0][i] > N[pid][i])
+		{
+			printf("\n ***Error encountered***\n");
+			exit(0);
+		}
+
+	for (i = 0; i < K; i++)
+		if (rmat[0][i] > B[0][i])
+		{
+			printf("\n ***Resources unavailable**\n");
+			exit(0);
+		}
+
+	for (i = 0; i < K; i++)
+	{
+		B[0][i] -= rmat[0][i];
+		A[pid][i] += rmat[0][i];
+		N[pid][i] -= rmat[0][i];
+	}
+}
+
+int banker(int A[][10], int N[][10],
+	int W[1][10], int n, int m)
+{
+	int j, i, a[10];
+	j = safety(A, N, W, n, m, a);
+	if (j != 0)
+	{
+		printf("\n\n");
+		printf("\n A safety sequence has been "
+			"detected.\n");
+		for (i = 0; i < n; i++)
+			printf(" P%d ", a[i]);
+		printf("\n");
+		return 1;
+	}
+	else
+	{
+		printf("\n Deadlock has occured.\n");
+		return 0;
+	}
+}
+
+int main()
+{
+	int All[10][10], Max[10][10], Need[10][10], W[1][10];
+	int n, m, pid, c, r;
+	printf("\n -----BANKER'S ALGORITHM-----\n");
+	Banker(All, Need, Max, W, &n, &m);
+	r = banker(All, Need, W, n, m);
+	if (r != 0)
+	{
+		printf("\n Do you want to continue?");
+		scanf("%d", &c);
+		if (c == 1)
+		{
+			printf("\n Enter process number : ");
+			scanf("%d", &pid);
+			request(All, Need, W, pid - 1, m);
+			r = banker(All, Need, W, n, m);
+			if (r == 0)
+			{
+				exit(0);
+			}
+		}
+	}
+	else
+		exit(0);
+	return 0;
+}