算法装载问题

算法设计与分析实验报告-
1.实验要求：
将n个集装箱装上载重量为c1和c2的轮船，其中集装箱总重量<c1+c2,使用回溯法求出最优装载方案。

3.程序代码
package javaapplication1;
import java.io.*;
public class Main {
static int n;
static int []w;
static int c1,c2;
static int cw;
static int bestw;
static int r;
static int []x;
static int []bestx;
public static int maxloading(int[]ww,int cc,int[]xx){
w=ww;
c1=cc;
bestw=0;
cw=0;
x=new int[n+1];
bestx=xx;
r=0;
for(int i=1;i<=n;i++)
r+=w[i];
backtrack(1);
return bestw;
}
private static void backtrack(int i){
if(i>n){ if(cw>bestw){
for(int j=1;j<=n;j++)
bestx[j]=x[j];
bestw=cw; }
return;
}
r-=w[i];
if(cw+w[i]<=c1){
x[i]=1;
cw+=w[i];
backtrack(i+1);
cw-=w[i];
}
if(cw+r>bestw){
x[i]=0;
backtrack(i+1);
}
r+=w[i]; }
public static void main(String[] args) throws IOException {
BufferedReader read =new BufferedReader(new InputStreamReader(new FileInputStream("input.txt")));
String a=new String();
a=read.readLine();
n=Integer.parseInt(a);
System.out.println("集装箱个数: "+n);
x=new int[n+1];
String[]b=new String[n];
a=read.readLine();
System.out.println("集装箱重量: "+a);
b=a.split(",");
w=new int[n+1];
for(int i=1;i<=n;i++){
w[i]=Integer.parseInt(b[i-1]);
}
a=read.readLine();
c1=Integer.parseInt(a);
a=read.readLine();
c2=Integer.parseInt(a);
System.out.println("轮船载重量: "+c1+","+c2);
int result= maxloading(w,c1,x);
int max,temp;
for(int i=1;i<3;i++){
for(int j=2;j<3;j++){
if(w[i]>w[j]){
temp=w[i];
w[i]=w[j];
w[j]=temp;
}
}
}
if((w[3]>c1)&&(w[3]>c2)){
System.out.println("都不可装");
}
else{System.out.println("轮船1装载的集装箱：");
for (int u=1;u<n+1;u++)
if(bestx[u]==1)
System.out.println(u+" ");
if(r>(result+c2))
System.out.println("轮船1可装："+result+" "+"轮船2装不完.");
else{
System.out.println("轮船2装载的集装箱：");
for (int u=1;u<n+1;u++)
if(bestx[u]==0)
System.out.println(u+" ");
System.out.println("最优装载--轮船1:"+result+" "+"轮船2:"+(r-result));
}
}
PrintWriter print=new PrintWriter(new OutputStreamWriter(new FileOutputStream("output.txt")));
if((w[3]>c1)&&(w[3]>c2)){
print.println("都不可装。

");
}
else{
print.println("轮船1装载的集装箱：");
for (int u=1;u<n+1;u++)
if(bestx[u]==1)
print.println(u+" ");
if(r>(result+c2))
print.println("轮船1可装："+result+" "+"轮船2装不完。

");
else{
print.println("轮船2装载的集装箱：");
for (int u=1;u<n+1;u++)
if(bestx[u]==0)
print.println(u+" ");
print.println("最优装载--轮船1:"+result+" "+"轮船2:"+(r-result));
}
}
read.close();
print.close(); }
}
2.程序流程图：
4.程序截图
input.txt
output.txt。