fork(1) download 
  1. #include <stdio.h>
  2. #include <stdbool.h>
  3.  
  4. // Maximum number of processes and resources
  5. #define MAX_PROCESSES 10
  6. #define MAX_RESOURCES 10
  7.  
  8. // Global variables
  9. int n, m; // Number of processes (n) and resource types (m)
  10. int Available[MAX_RESOURCES];
  11. int Max[MAX_PROCESSES][MAX_RESOURCES];
  12. int Allocation[MAX_PROCESSES][MAX_RESOURCES];
  13. int Need[MAX_PROCESSES][MAX_RESOURCES];
  14.  
  15. // Function to calculate the Need matrix
  16. void calculateNeed() {
  17.     for (int i = 0; i < n; i++)
  18.         for (int j = 0; j < m; j++)
  19.             Need[i][j] = Max[i][j] - Allocation[i][j];
  20. }
  21.  
  22. // Safety Algorithm to check if the system is in a safe state
  23. bool isSafe() {
  24.     int Work[MAX_RESOURCES];
  25.     bool Finish[MAX_PROCESSES];
  26.     int safeSequence[MAX_PROCESSES];
  27.     int count = 0;
  28.  
  29.     // Initialize Work = Available and Finish = false
  30.     for (int j = 0; j < m; j++)
  31.         Work[j] = Available[j];
  32.     for (int i = 0; i < n; i++)
  33.         Finish[i] = false;
  34.  
  35.     // Safety algorithm
  36.     while (count < n) {
  37.         bool found = false;
  38.         for (int i = 0; i < n; i++) {
  39.             if (!Finish[i]) {
  40.                 bool canAllocate = true;
  41.                 for (int j = 0; j < m; j++) {
  42.                     if (Need[i][j] > Work[j]) {
  43.                         canAllocate = false;
  44.                         break;
  45.                     }
  46.                 }
  47.                 if (canAllocate) {
  48.                     for (int j = 0; j < m; j++)
  49.                         Work[j] += Allocation[i][j];
  50.                     safeSequence[count] = i;
  51.                     Finish[i] = true;
  52.                     count++;
  53.                     found = true;
  54.                 }
  55.             }
  56.         }
  57.         if (!found) {
  58.             printf("System is not in a safe state.\n");
  59.             return false;
  60.         }
  61.     }
  62.  
  63.     // Print safe sequence
  64.     printf("System is in a safe state.\nSafe sequence: ");
  65.     for (int i = 0; i < n; i++)
  66.         printf("P%d ", safeSequence[i]);
  67.     printf("\n");
  68.     return true;
  69. }
  70.  
  71. // Resource Request Algorithm
  72. void requestResources(int process, int Request[]) {
  73.     // Step 1: Check if Request <= Need
  74.     for (int j = 0; j < m; j++) {
  75.         if (Request[j] > Need[process][j]) {
  76.             printf("Error: Request exceeds maximum need for process P%d.\n", process);
  77.             return;
  78.         }
  79.     }
  80.  
  81.     // Step 2: Check if Request <= Available
  82.     for (int j = 0; j < m; j++) {
  83.         if (Request[j] > Available[j]) {
  84.             printf("Resources not available. Process P%d must wait.\n", process);
  85.             return;
  86.         }
  87.     }
  88.  
  89.     // Step 3: Pretend to allocate resources
  90.     for (int j = 0; j < m; j++) {
  91.         Available[j] -= Request[j];
  92.         Allocation[process][j] += Request[j];
  93.         Need[process][j] -= Request[j];
  94.     }
  95.  
  96.     // Check if the resulting state is safe
  97.     if (isSafe()) {
  98.         printf("Request granted for process P%d.\n", process);
  99.     } else {
  100.         // Restore the previous state
  101.         for (int j = 0; j < m; j++) {
  102.             Available[j] += Request[j];
  103.             Allocation[process][j] -= Request[j];
  104.             Need[process][j] += Request[j];
  105.         }
  106.         printf("Request denied for process P%d. System would be unsafe.\n", process);
  107.     }
  108. }
  109.  
  110. int main() {
  111.     // Input number of processes and resources
  112.     printf("Enter number of processes: ");
  113.     scanf("%d", &n);
  114.     printf("Enter number of resource types: ");
  115.     scanf("%d", &m);
  116.  
  117.     // Input Available resources
  118.     printf("Enter Available resources (for %d resource types):\n", m);
  119.     for (int j = 0; j < m; j++) {
  120.         printf("Resource %d: ", j);
  121.         scanf("%d", &Available[j]);
  122.     }
  123.  
  124.     // Input Max matrix
  125.     printf("Enter Max matrix (%d processes x %d resources):\n", n, m);
  126.     for (int i = 0; i < n; i++)
  127.         for (int j = 0; j < m; j++) {
  128.             printf("Max[P%d][R%d]: ", i, j);
  129.             scanf("%d", &Max[i][j]);
  130.         }
  131.  
  132.     // Input Allocation matrix
  133.     printf("Enter Allocation matrix (%d processes x %d resources):\n", n, m);
  134.     for (int i = 0; i < n; i++)
  135.         for (int j = 0; j < m; j++) {
  136.             printf("Allocation[P%d][R%d]: ", i, j);
  137.             scanf("%d", &Allocation[i][j]);
  138.         }
  139.  
  140.     // Calculate Need matrix
  141.     calculateNeed();
  142.  
  143.     // Display matrices
  144.     printf("\nMax Matrix:\n");
  145.     for (int i = 0; i < n; i++) {
  146.         for (int j = 0; j < m; j++)
  147.             printf("%d ", Max[i][j]);
  148.         printf("\n");
  149.     }
  150.  
  151.     printf("\nAllocation Matrix:\n");
  152.     for (int i = 0; i < n; i++) {
  153.         for (int j = 0; j < m; j++)
  154.             printf("%d ", Allocation[i][j]);
  155.         printf("\n");
  156.     }
  157.  
  158.     printf("\nNeed Matrix:\n");
  159.     for (int i = 0; i < n; i++) {
  160.         for (int j = 0; j < m; j++)
  161.             printf("%d ", Need[i][j]);
  162.         printf("\n");
  163.     }
  164.  
  165.     printf("\nAvailable Resources: ");
  166.     for (int j = 0; j < m; j++)
  167.         printf("%d ", Available[j]);
  168.     printf("\n");
  169.  
  170.     // Check if the initial state is safe
  171.     isSafe();
  172.  
  173.     // Input resource request
  174.     int process;
  175.     printf("\nEnter process number for resource request (0 to %d): ", n - 1);
  176.     scanf("%d", &process);
  177.     int Request[MAX_RESOURCES];
  178.     printf("Enter Request vector for P%d (for %d resources):\n", process, m);
  179.     for (int j = 0; j < m; j++) {
  180.         printf("Request[R%d]: ", j);
  181.         scanf("%d", &Request[j]);
  182.     }
  183.  
  184.     // Process the resource request
  185.     requestResources(process, Request);
  186.  
  187.     return 0;
  188. }
Success #stdin #stdout 0s 5320KB
comments (?)
stdin 
Standard input is empty
stdout 
Enter number of processes: Enter number of resource types: Enter Available resources (for 0 resource types):
Enter Max matrix (0 processes x 0 resources):
Enter Allocation matrix (0 processes x 0 resources):

Max Matrix:

Allocation Matrix:

Need Matrix:

Available Resources: 
System is in a safe state.
Safe sequence: 

Enter process number for resource request (0 to -1): Enter Request vector for P0 (for 0 resources):
System is in a safe state.
Safe sequence: 
Request granted for process P0.
https://ideone.com/P3ci5R
language:
C (gcc 8.3)
created:
6 days ago
visibility:
public

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