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最长公共子序列

程序员文章站 2024-03-17 22:00:22
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public class Lcs {
	public static int LcsLength(String[] x, String[] 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 static void lcs(int i,int j,String[] x,int [][]b)
	{
		if(i==0||j==0)return;
		if(b[i][j]==1) {
			lcs(i-1, j-1, x, b);
			System.out.println(x[i]);
		}
		else if(b[i][j]==2)lcs(i-1, j, x, b);
		else lcs(i,j-1,x,b);
	}
	public static void main(String args[]) {
	    System.out.println("测试结果:");
	    String[] x = {" ","A", "B", "C", "B", "D", "A", "B"};
	    String[] y = {" ","B", "D", "C", "A", "B", "A"};
	    int[][] b = new int[x.length][y.length];
	    int c = LcsLength(x, y,b);
	    System.out.println("X和y的最长公共子序列是:");
	    lcs(x.length - 1, y.length - 1,x,b);
	  }

}
相关标签: 最长公共子序列