weightedjobscheduling.cpp

Given some jobs with its start time,finish time and profit.we have to maximize the profit.

Author: souravmondaldev

weightedjobscheduling.cpp

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+// C++ program for weighted job scheduling using Naive Recursive Method 
+#include<bits/stdc++.h>
+#include <iostream> 
+#include <algorithm> 
+using namespace std; 
+
+// A job has start time, finish time and profit. 
+struct Job 
+{ 
+	int start, finish, profit; 
+}; 
+
+// A utility function that is used for sorting events 
+// according to finish time 
+bool jobComparataor(Job s1, Job s2) 
+{ 
+	return (s1.finish < s2.finish); 
+} 
+
+// Find the latest job (in sorted array) that doesn't 
+// conflict with the job[i]. If there is no compatible job, 
+// then it returns -1. 
+int latestNonConflict(Job arr[], int i) 
+{ 
+	for (int j=i-1; j>=0; j--) 
+	{ 
+		if (arr[j].finish <= arr[i-1].start) 
+			return j; 
+	} 
+	return -1; 
+} 
+
+// A recursive function that returns the maximum possible 
+// profit from given array of jobs. The array of jobs must 
+// be sorted according to finish time. 
+int findMaxProfitRec(Job arr[], int n) 
+{ 
+	// Base case 
+	if (n == 1) return arr[n-1].profit; 
+
+	// Find profit when current job is inclueded 
+	int inclProf = arr[n-1].profit; 
+  
+	int i = latestNonConflict(arr, n);
+  
+	if (i != -1) {
+	inclProf += findMaxProfitRec(arr, i+1); 
+  }
+
+	// Find profit when current job is excluded 
+	int exclProf = findMaxProfitRec(arr, n-1); 
+
+	return max(inclProf, exclProf); 
+} 
+
+// The main function that returns the maximum possible  profit from given array of jobs 
+
+
+int findMaxProfit(Job arr[], int n) 
+{ 
+	// Sort jobs according to finish time 
+	sort(arr, arr+n, jobComparataor); 
+
+	return findMaxProfitRec(arr, n); 
+} 
+
+
+// Driver program 
+int main() 
+{ 
+  Job arr[] = {{3, 10, 20}, {1, 2, 50}, {6, 19, 100}, {2, 100, 200}}; 
+	int n = sizeof(arr)/sizeof(arr[0]); 
+	cout << "The optimal profit is " << findMaxProfit(arr, n); 
+  
+	return 0; 
+}