lcs.java

用动态怪话编写的有关最优公共秩序列问题的java程序

public class Lcs
{
	
	public int lcsLength(char[]x,char []y,int [][]b)
	{
		int m = x.length - 1;
	    int n = y.length - 1;
	    int [][]c = new int [m+1][n+1];
	    for (int i = 1;i <= m;i++)   c[i][0] = 0;
		for (int i = 1;i <= n;i++)   c[0][i] = 0;
		for (int i = 1;i <= m;i++)
		    for (int j = 1;j <= n;j++)
		    {  if (x[i] == y[j])
		      {
		      	c[i][j] = c[i - 1][j - 1] + 1;
                b[i][j]	= 1;
                }
              else if (c[i-1][j] >= c[i][j-1])
              {
              	c[i][j] = c[i - 1][j];
              	b[i][j] = 2;
              }
              else
              {
              	c[i][j] = c[i][j - 1];              	
              	b[i][j] = 3;
              }
            }
            return c[m][n];
            
      	  }
      public void lcs1(int i,int j,char []x,int [][]b)
      {
      	if (i == 0 || j == 0) return;
      	if (b[i][j] == 1)
      	{
      		lcs1(i-1,j-1,x,b);
      		System.out.print(x[i]);
      		
      	}
      	else if (b[i][j] == 2) lcs1(i - 1,j,x,b);
      	  else lcs1(i,j - 1,x,b);
      }
    
      
      public static void main(String args[])
      {
      	 char x[] = {' ','a','b','d','e','z'};
      	 char y[] = {' ','b','d','e','s','g','z'};	  
      	 int b[][] = new int[x.length][y.length];
      	 int i,j;
      	 Lcs l = new Lcs();
      	 System.out.print(l.lcsLength(x,y,b));
      	 System.out.println();
      	 System.out.println();
      	 System.out.println();
      	 System.out.println();
      	 System.out.println();   
      	 l.lcs1(5,6,x,b);
      }
}