ADA Program 7

 

7. Fractional / Continuous Knapsack (Greedy)

#include <stdio.h>

typedef struct {
    int id;
    float weight;
    float profit;
    float ratio;
} Item;

void sortItems(Item items[], int n) {
    for (int i = 0; i < n - 1; i++) {
        for (int j = i + 1; j < n; j++) {
            if (items[i].ratio < items[j].ratio) {
                Item temp = items[i];
                items[i] = items[j];
                items[j] = temp;
            }
        }
    }
}

void discreteKnapsackGreedy(Item items[], int n, float capacity) {
    float totalProfit = 0.0f;
    float remaining = capacity;
    for (int i = 0; i < n; i++) {
        if (items[i].weight <= remaining) {
            remaining = remaining-items[i].weight;
            totalProfit =totalProfit+ items[i].profit;
        }
    }
    printf("Discrete (0/1) Greedy Approximation Profit: %f \n", totalProfit);
}

void continuousKnapsack(Item items[], int n, float capacity) {
    float totalProfit = 0.0f;
    float remaining = capacity;
    for (int i = 0; i < n; i++) {
        if (items[i].weight <= remaining) {
            remaining = remaining-items[i].weight;
            totalProfit = totalProfit+ items[i].profit;
        } else if (remaining > 0) {
            totalProfit = totalProfit+ items[i].profit * (remaining / items[i].weight);
            break;
        }
    }
    printf("\n Continuous (Fractional) Knapsack Profit: %.2f\n", totalProfit);
}

int main() {
    int n;
    float capacity;
    printf("Enter number of items: ");
    scanf("%d", &n);
    Item items[n];
    for (int i = 0; i < n; i++) {
        items[i].id = i + 1;
        printf("Enter weight and profit for item %d: ", i + 1);
        scanf("%f %f", &items[i].weight, &items[i].profit);
        items[i].ratio = items[i].profit / items[i].weight;
    }
    printf("Enter knapsack capacity: ");
    scanf("%f", &capacity);
    sortItems(items, n);
    discreteKnapsackGreedy(items, n, capacity);
    continuousKnapsack(items, n, capacity);
    return 0;
}
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