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FractionalKnapsack.java
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FractionalKnapsack.java
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package fractionalKnapsack;
import java.util.Arrays;
import java.util.Comparator;
//Greedy approach
public class FractionalKnapsack
{
// function to get maximum value
private static double getMaxValue(int[] wt, int[] val,
int capacity)
{
ItemValue[] iVal = new ItemValue[wt.length];
for (int i = 0; i < wt.length; i++) {
iVal[i] = new ItemValue(wt[i], val[i], i);
}
// sorting items by value;
Arrays.sort(iVal, new Comparator<ItemValue>() {
@Override
public int compare(ItemValue o1, ItemValue o2)
{
return o2.cost.compareTo(o1.cost);
}
});
double totalValue = 0d;
for (ItemValue i : iVal) {
int curWt = (int)i.wt;
int curVal = (int)i.val;
if (capacity - curWt >= 0)
{
// this weight can be picked while
capacity = capacity - curWt;
totalValue += curVal;
}
else
{
// item cant be picked whole
double fraction
= ((double)capacity / (double)curWt);
totalValue += (curVal * fraction);
capacity
= (int)(capacity - (curWt * fraction));
break;
}
}
return totalValue;
}
// item value class
static class ItemValue
{
Double cost;
double wt, val, ind;
// item value function
public ItemValue(int wt, int val, int ind)
{
this.wt = wt;
this.val = val;
this.ind = ind;
cost = new Double((double)val / (double)wt);
}
}
// Driver code
public static void main(String[] args)
{
int[] wt = { 10, 40, 20, 30 };
int[] val = { 60, 40, 100, 120 };
int capacity = 50;
double maxValue = getMaxValue(wt, val, capacity);
// Function call
System.out.println("Maximum value we can obtain = "
+ maxValue);
}
}