Create main.cpp

Author: JawadSher

25 - Greedy Algorithm Problems/11 - Job Sequencing Problem/main.cpp

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+class Solution {
+  public:
+    vector<int> JobSequencing(vector<int> &id, vector<int> &deadline,
+                              vector<int> &profit) {
+        
+        // Step 1: Create a vector of tuples to store job details (profit, job id, and deadline)
+        vector<tuple<int, int, int>> v;
+        
+        // Loop through the job arrays and create tuples of (profit, job id, deadline)
+        for(int i = 0; i < id.size(); i++){
+            v.push_back(make_tuple(profit[i], id[i], deadline[i]));
+        }
+        
+        // Step 2: Sort the jobs by profit in descending order
+        // The job with higher profit is considered first
+        sort(v.begin(), v.end(), [](tuple<int, int, int>& a, tuple<int, int, int>& b){
+            return get<0>(a) > get<0>(b);  // Compare based on profit (first element of the tuple)
+        });
+        
+        // Step 3: Find the maximum deadline to define the size of the schedule array
+        int maxiDeadline = INT_MIN;
+        for(int i = 0; i < deadline.size(); i++){
+            maxiDeadline = max(maxiDeadline, deadline[i]);
+        }
+        
+        // Step 4: Initialize the schedule array with -1 to represent unoccupied time slots
+        // The array has size `maxiDeadline + 1` because deadlines are 1-based.
+        vector<int> schedule(maxiDeadline+1, -1);
+        
+        // Step 5: Initialize variables to track the number of jobs selected and total profit
+        int count = 0;
+        int maxProfit = 0;
+        
+        // Step 6: Try to schedule jobs in decreasing order of their profit
+        for(int i = 0; i < v.size(); i++){
+            int currProfit = get<0>(v[i]);   // Profit of the current job
+            int currJobId = get<1>(v[i]);    // Job id of the current job
+            int currDeadline = get<2>(v[i]); // Deadline of the current job
+            
+            // Step 7: Try to find the latest available time slot before the job's deadline
+            for(int k = currDeadline; k > 0; k--){
+                // If the time slot is free (schedule[k] == -1), schedule the job there
+                if(schedule[k] == -1){
+                    schedule[k] = currJobId; // Assign the job id to the available slot
+                    maxProfit += currProfit; // Add the profit of the job to the total profit
+                    count++;                // Increment the count of scheduled jobs
+                    break;                  // Break out of the loop after scheduling the job
+                }
+            }    
+        }
+        
+        // Step 8: Return the count of jobs scheduled and the total profit
+        return {count, maxProfit};
+    }
+};