Greedy Algorithms -> greedy_algorithms (#647)

greedy_algorithms/Knapsack.cpp

@@ -0,0 +1,92 @@
+#include <iostream>
+using namespace std;
+
+struct Item
+{
+	int weight;
+	int profit;
+};
+
+float profitPerUnit(Item x)
+{
+	return (float)x.profit / (float)x.weight;
+}
+
+int partition(Item arr[], int low, int high)
+{
+	Item pivot = arr[high]; // pivot
+	int i = (low - 1);		// Index of smaller element
+
+	for (int j = low; j < high; j++)
+	{
+		// If current element is smaller than or
+		// equal to pivot
+		if (profitPerUnit(arr[j]) <= profitPerUnit(pivot))
+		{
+			i++; // increment index of smaller element
+			Item temp = arr[i];
+			arr[i] = arr[j];
+			arr[j] = temp;
+		}
+	}
+	Item temp = arr[i + 1];
+	arr[i + 1] = arr[high];
+	arr[high] = temp;
+	return (i + 1);
+}
+
+void quickSort(Item arr[], int low, int high)
+{
+	if (low < high)
+	{
+
+		int p = partition(arr, low, high);
+
+		quickSort(arr, low, p - 1);
+		quickSort(arr, p + 1, high);
+	}
+}
+
+int main()
+{
+	cout << "\nEnter the capacity of the knapsack : ";
+	float capacity;
+	cin >> capacity;
+	cout << "\n Enter the number of Items : ";
+	int n;
+	cin >> n;
+	Item itemArray[n];
+	for (int i = 0; i < n; i++)
+	{
+		cout << "\nEnter the weight and profit of item " << i + 1 << " : ";
+		cin >> itemArray[i].weight;
+		cin >> itemArray[i].profit;
+	}
+
+	quickSort(itemArray, 0, n - 1);
+
+	// show(itemArray, n);
+
+	float maxProfit = 0;
+	int i = n;
+	while (capacity > 0 && --i >= 0)
+	{
+		if (capacity >= itemArray[i].weight)
+		{
+			maxProfit += itemArray[i].profit;
+			capacity -= itemArray[i].weight;
+			cout << "\n\t" << itemArray[i].weight << "\t" << itemArray[i].profit;
+		}
+		else
+		{
+			maxProfit += profitPerUnit(itemArray[i]) * capacity;
+			cout << "\n\t" << capacity << "\t" << profitPerUnit(itemArray[i]) * capacity;
+			capacity = 0;
+			break;
+		}
+	}
+
+	cout << "\nMax Profit : " << maxProfit;
+
+	return 0;
+}