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  1. #include <iostream>
  2. using namespace std;
  3.  
  4. const int P = 5; // Number of processes
  5. const int R = 3; // Number of resources
  6.  
  7. // Function to find the safe sequence
  8. void findSafeSequence(int processes[], int available[], int max[][R], int allot[][R]) {
  9.     int need[P][R];
  10.  
  11.     // Calculate need matrix
  12.     for (int i = 0; i < P; i++)
  13.         for (int j = 0; j < R; j++)
  14.             need[i][j] = max[i][j] - allot[i][j];
  15.  
  16.     bool finish[P] = {false};
  17.     int safeSeq[P];
  18.     int work[R];
  19.  
  20.     for (int i = 0; i < R; i++)
  21.         work[i] = available[i];
  22.  
  23.     int count = 0;
  24.     while (count < P) {
  25.         bool found = false;
  26.         for (int p = 0; p < P; p++) {
  27.             if (!finish[p]) {
  28.                 bool canRun = true;
  29.                 for (int j = 0; j < R; j++) {
  30.                     if (need[p][j] > work[j]) {
  31.                         canRun = false;
  32.                         break;
  33.                     }
  34.                 }
  35.  
  36.                 if (canRun) {
  37.                     for (int k = 0; k < R; k++)
  38.                         work[k] += allot[p][k];
  39.  
  40.                     safeSeq[count++] = p;
  41.                     finish[p] = true;
  42.                     found = true;
  43.                 }
  44.             }
  45.         }
  46.  
  47.         if (!found) {
  48.             cout << "System is in an unsafe state. No safe sequence exists.\n";
  49.             return;
  50.         }
  51.     }
  52.  
  53.     cout << "System is in a safe state.\nSafe sequence is: ";
  54.     for (int i = 0; i < P; i++)
  55.         cout << "P" << safeSeq[i] << " ";
  56.     cout << endl;
  57. }
  58.  
  59. int main() {
  60.     int processes[] = {0, 1, 2, 3, 4};
  61.  
  62.     int available[R] = {3, 3, 2};
  63.  
  64.     int max[P][R] = {
  65.         {7, 5, 3},
  66.         {3, 2, 2},
  67.         {9, 0, 2},
  68.         {2, 2, 2},
  69.         {4, 3, 3}
  70.     };
  71.  
  72.     int allot[P][R] = {
  73.         {0, 1, 0},
  74.         {2, 0, 0},
  75.         {3, 0, 2},
  76.         {2, 1, 1},
  77.         {0, 0, 2}
  78.     };
  79.  
  80.     findSafeSequence(processes, available, max, allot);
  81.     return 0;
  82. }
  83.  
Success #stdin #stdout 0.01s 5276KB
comments (?)
stdin 
Standard input is empty
stdout 
System is in a safe state.
Safe sequence is: P1 P3 P4 P0 P2
https://ideone.com/KOgrjC
language:
C++ (gcc 8.3)
created:
3 days ago
visibility:
public

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