Create priority_scheduling_algo.cpp

Algorithms/CPU Scheduling/priority_scheduling_algo.cpp

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+// Priority Scheduling Algorithm
+#include <iostream>
+
+int main() {
+
+  int* bt  = nullptr; // burst time
+  int* wt  = nullptr; // wait time
+  int* tat = nullptr; // turn around time
+  int* pr  = nullptr; // priority
+  int* p   = nullptr; // process number
+
+  int n; // number of processes
+
+  int i, j;
+
+  int total   = 0;
+  int avg_wt  = 0; // average waiting time
+  int avg_tat = 0; // average turnaround time
+
+  std::cout << "\nEnter total number of processes\n";
+  std::cin >> n;
+
+  bt  = new int[n]; // Allocate n ints and save ptr in array
+  wt  = new int[n];
+  tat = new int[n];
+  pr  = new int[n];
+  p   = new int[n];
+
+  for(int i = 0; i < n; ++i) {
+    bt[i]  = 0; // Initialize all elements to zero
+    wt[i]  = 0;
+    tat[i] = 0;
+    pr[i]  = 0;
+    p[i]   = 0;
+  }
+
+  std::cout << "\nEnter Burst Time and Priority:\n";
+  for(i = 0; i < n; ++i) {
+    std::cout<<"\nP["<<i+1<<"]\n";
+    std::cout<<"Burst Time:";
+    std::cin>>bt[i];
+    std::cout<<"Priority:";
+    std::cin>>pr[i];
+    p[i]=i+1;           //contains process number
+  }
+
+  //sorting burst time, priority and process number in ascending order using selection sort
+  for(i = 0; i < n; ++i) {
+    int pos = i;
+    for(j = i + 1; j < n; ++j) {
+      if(pr[j] < pr[pos])
+        pos = j;
+    }
+
+    int temp = pr[i];
+    pr[i] = pr[pos];
+    pr[pos] = temp;
+
+    temp = bt[i];
+    bt[i] = bt[pos];
+    bt[pos] =temp;
+
+    temp = p[i];
+    p[i] = p[pos];
+    p[pos] = temp;
+  }
+
+  wt[0] = 0; //waiting time for first process is zero
+
+  //calculate waiting time
+  for(i = 1; i < n; ++i) {
+    wt[i] = 0;
+    for(j = 0; j < i; ++j)
+      wt[i] += bt[j];
+
+    total += wt[i];
+  }
+
+  avg_wt = total/n; //average waiting time
+  total = 0;
+
+  std::cout<<"\nProcess\tBurst Time\tWaiting Time\tTurnaround Time";
+  for(i = 0; i < n; ++i) {
+    tat[i] = bt[i] + wt[i]; //calculate turnaround time
+    total += tat[i];
+    std::cout<<"\nP[" << p[i] << "]\t\t" << bt[i] << "\t\t" <<wt[i] << "\t\t\t" <<tat[i];
+  }
+
+  avg_tat=total/n; //average turnaround time
+  std::cout<<"\n\nAverage Waiting Time="<<avg_wt;
+  std::cout<<"\nAverage Turnaround Time="<<avg_tat;
+
+  // Free memory and clear to prevent access to invalid memory
+  bt = nullptr;
+  delete bt;
+  wt = nullptr;
+  delete wt;
+  tat = nullptr;
+  delete tat;
+  return 0;
+  delete pr;
+  return 0;
+  delete p;
+  return 0;
+}