0-1背包问题（贪心法）

public class Package2 {

        public static void main(String[] args) {
            Scanner in = new Scanner(System.in);
            System.out.println("请输入物品的数量:");
            int n = in.nextInt();
            int[] w = new int[n];
            int[] v = new int[n];
            System.out.println("现在请输入这些物品的重量:");
            for (int i = 0; i < n; i++) {
                w[i] = in.nextInt();
            }
            System.out.println("现在请输入这些物品的价值:");
            for (int i = 0; i < n; i++) {
                v[i] = in.nextInt();
            }
            System.out.println("现在请输入背包的容量:");
            int c = in.nextInt();
            /**
             *按单位重量价值r[i]=v[i]/w[i]降序排列
             */

            double[] r = new double[n];
            int[] index = new int[n];
            for (int i = 0; i < n; i++) {
                r[i] = (double) v[i] / (double) w[i];
                index[i] = i;
            }
            double temp = 0;
            //降序排列
            for (int i = 0; i < n - 1; i++) {
                for (int j = i + 1; j < n; j++) {
                    if (r[i] < r[j]) {
                        temp = r[i];
                        r[i] = r[j];
                        r[j] = temp;
                        //交换i，j的下标
                        int x = index[i];
                        index[i] = index[j];
                        index[j] = x;
                    }
                }
            }
            /**
             *排序后的重量和价值分别存到w1[]和v1[]中
             */
            int[] w1 = new int[n];
            int[] v1 = new int[n];
            int maxValue = 0;
            for (int i = 0; i < n; i++) {
                w1[i] = w[index[i]];
                v1[i] = v[index[i]];
            }
            System.out.println(Arrays.toString(w1));
            System.out.println(Arrays.toString(v1));
            /**
             *初始化解向量x[n]
             */
            int[] x = new int[n];
            for (int i = 0; i < n; i++) {
                x[i] = 0;
            }
            /**
             *求解并打印解向量
             */
            for (int i = 0; i < n; i++) {
                if (w1[i] < c) {
                    x[i] = 1;
                    c = c - w1[i];
                    maxValue += v1[i];
                }
                else{
                    x[i] = c/w[index[i]];
                    maxValue += x[i]*v[index[i]];
                    //break; 去掉这个就好
                }


            }



            System.out.println("解向量是:" + Arrays.toString(x));
            /**
             *根据解向量求出背包中存放物品的最大价值并打印
             */



            System.out.println("背包中物品的最大价值为:" + maxValue);

        }
}