解决分数背包问题的C ++程序
在小背包问题中，给出了一组项目，每个项目都有一个权重和一个值。我们需要打破物品以最大化背包的总值，这可以通过贪婪的方法来完成。
算法
Begin Take an array of structure Item Declare value, weight, knapsack weight and density Calculate density=value/weight for each item Sorting the items array on the order of decreasing density We add values from the top of the array to total value until the bag is full, i.e; total value <= W End
范例程式码
#include <iostream>
#include <bits/stdc++.h>
using namespace std;
typedef struct {
int v;
int w;
float d;
} Item;
void input(Item items[],int sizeOfItems) {
cout << "Enter total "<< sizeOfItems <<" item's values and weight" <<
endl;
for(int I = 0; I < sizeOfItems; i++) {
cout << "Enter "<< i+1 << " V ";
cin >> items[i].v;
cout << "Enter "<< i+1 << " W";
cin >> items[i].w;
}
}
void display(Item items[], int sizeOfItems) {
int i;
cout << "values: ";
for(i = 0; i < sizeOfItems; i++) {
cout << items[i].v << "\t";
}
cout << endl << "weight: ";
for (I = 0; I < sizeOfItems; i++) {
cout << items[i].w << "\t";
}
cout << endl;
}
bool compare(Item i1, Item i2) {
return (i1.d > i2.d);
}
float knapsack(Item items[], int sizeOfItems, int W) {
int i, j, pos;
Item mx, temp;
float totalValue = 0, totalWeight = 0;
for (i = 0; i < sizeOfItems; i++) {
items[i].d = items[i].v / items[i].w;
}
sort(items, items+sizeOfItems, compare);
for(i=0; i<sizeOfItems; i++) {
if(totalWeight + items[i].w<= W) {
totalValue += items[i].v ;
totalWeight += items[i].w;
} else {
int wt = W-totalWeight;
totalValue += (wt * items[i].d);
totalWeight += wt;
break;
}
}
cout << "total weight in bag " << totalWeight<<endl;
return totalValue;
}
int main() {
int W;
Item items[4];
input(items, 4);
cout << "Entered data \n";
display(items,4);
cout<< "Enter Knapsack weight \n";
cin >> W;
float mxVal = knapsack(items, 4, W);
cout << "Max value for "<< W <<" weight is "<< mxVal;
}输出结果
Enter total 4 item's values and weight Enter 1 V 50 Enter 1 W 10 Enter 2 V 60 Enter 2 W 20 Enter 3 V 70 Enter 3 W 30 Enter 4 V 70 Enter 4 W 40 Entered data values: 50 60 70 70 weight: 10 20 30 40 Enter Knapsack weight 60 total weight in bag 60 Max value for 60 weight is 180
热门推荐
10 朋友新年祝福语大全 简短
11 新年祝福语简短大方兔年
12 搬新家礼物祝福语简短
13 同学见面花束祝福语简短
14 五一假期祝福语幽默简短
15 离职欢送敬酒祝福语简短
16 对学弟的祝福语简短
17 考老师辞职祝福语简短
18 祝福语驱散霉运的话简短