贪心法求解背包问题(部分背包 物品可分)

/**
* @file				Greedy1Knapsack.cpp
* @brief			solve a question of Knapsack by using "select max value"'s way
* @author			taoxiaoxiao/Univ.
* @date				11-3-2013
*/
//输入实例 W=50 v=[60,150,150] w=[10,20,50]
//该算法求解部分背包(物品可分)
//该算法每次选择最大价值（不是最优解）
#include <iostream>
#include <algorithm>
#define N 3
using namespace std;

int v
, w
;
double  x
;
int W = 50;

void sort(int v[], int w[])
{
int tmp1, tmp2;
int i, j;

for (i = 0; i < N - 1; ++i)
{
int k = i;
for (j = i + 1; j < N; ++j)
{
if (v[j] > v[k])
k = j;
}
if (k != i)
{
tmp1 = v[i], tmp2 = w[i];
v[i] = v[k], w[i] = w[k];
v[k] = tmp1, w[k] = tmp2;
}
}
}

void Greedy1Knapsack()
{
int i;

for (i = 0; i < N; ++i)
{
if (w[i]>W)
break;
x[i] = 1;
W -= w[i];
}
if (i <= N)
x[i] = double(W) / w[i];
}

int main()
{
int i;
double max_value = 0.0;

for (i = 0; i < N; ++i)
cin >> v[i];
for (i = 0; i < N; ++i)
cin >> w[i];
sort(v,w);
Greedy1Knapsack();
for (i = 0; i < N; ++i)
{
if (x[i] > 0)
{
cout << "[" << v[i] << "," << w[i] << "]"
<< "放入" << x[i] << "件" << "\n";
max_value += x[i] * v[i];
}
}
cout << "最大价值为:" << max_value << endl;

return 0;
}