背包问题_最优解法

package qinglin.learn.arithmetic;

public class SackPro_02
{
	int p[] =new int[]{9,10,7,4};
	
	int w[] =new int[]{3,5,2,1};
	
	int cp[]=new int[p.length];
	
	int cw[]=new int[w.length];
	
	int x[]=new int[p.length];
	
	int cx[]=new int[p.length];
	
	int currentP,currentW,bestp;
	
	private void printResult()
	{   
		 System.out.println("可以装入的最大价值为:"+bestp);   
		
		 System.out.println("装入的物品依次为:");   
		 
		 for(int i = 0; i < x.length; i++)
		 {
			 if(x[i]==1)
				 System.out.print((i+1)+"  ");
		 }   
	}   	
	void backtrack(int i)
	 {
		 if(i >= 4)
		 {
			 if(currentP > bestp)
			 {
				 bestp = currentP;
				 
				 for(int j = 0; j < 4; j++)   
				
				 x[j] = cx[j];
			 }
			 return;
		 }
		 if(currentW + w[i] <= 7)
		 {//搜索右子树
			 currentW += w[i];   
			 currentP += p[i];   
			 cx[i] = 1;   
			 backtrack(i+1);   
			 currentW -= w[i];   
			 currentP -= p[i];   
			 cx[i] = 0; 
		 }
		backtrack(i+1);//搜索左子树   
	 }
	public static void main(String[] args)
	{
		SackPro_02 example = new SackPro_02();
		example.backtrack(0);
		example.printResult();
	}
}