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// C/C++ program to solve fractional Knapsack Problem | ||
#include <bits/stdc++.h> | ||
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using namespace std; | ||
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// Structure for an item which stores weight and corresponding | ||
// value of Item | ||
struct Item | ||
{ | ||
int value, weight; | ||
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// Constructor | ||
Item(int value, int weight) : value(value), weight(weight) | ||
{} | ||
}; | ||
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// Comparison function to sort Item according to val/weight ratio | ||
bool cmp(struct Item a, struct Item b) | ||
{ | ||
double r1 = (double)a.value / a.weight; | ||
double r2 = (double)b.value / b.weight; | ||
return r1 > r2; | ||
} | ||
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// Main greedy function to solve problem | ||
double fractionalKnapsack(int W, struct Item arr[], int n) | ||
{ | ||
// sorting Item on basis of ratio | ||
sort(arr, arr + n, cmp); | ||
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// Uncomment to see new order of Items with their ratio | ||
/* | ||
for (int i = 0; i < n; i++) | ||
{ | ||
cout << arr[i].value << " " << arr[i].weight << " : " | ||
<< ((double)arr[i].value / arr[i].weight) << endl; | ||
} | ||
*/ | ||
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int curWeight = 0; // Current weight in knapsack | ||
double finalvalue = 0.0; // Result (value in Knapsack) | ||
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// Looping through all Items | ||
for (int i = 0; i < n; i++) | ||
{ | ||
// If adding Item won't overflow, add it completely | ||
if (curWeight + arr[i].weight <= W) | ||
{ | ||
curWeight += arr[i].weight; | ||
finalvalue += arr[i].value; | ||
} | ||
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// If we can't add current Item, add fractional part of it | ||
else | ||
{ | ||
int remain = W - curWeight; | ||
finalvalue += arr[i].value * ((double) remain / arr[i].weight); | ||
break; | ||
} | ||
} | ||
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// Returning final value | ||
return finalvalue; | ||
} | ||
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// driver program to test above function | ||
int main() | ||
{ | ||
int W = 50; // Weight of knapsack | ||
Item arr[] = {{60, 10}, {100, 20}, {120, 30}}; | ||
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int n = sizeof(arr) / sizeof(arr[0]); | ||
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cout << "Maximum value we can obtain = " | ||
<< fractionalKnapsack(W, arr, n); | ||
return 0; | ||
} |