Java求最长公共子序列的长度

public class LCS {
	private enum Path {TOP, LEFT, TOP_LEFT};
	private static int[][] commonLenth;
	private static Path[][] path;
	private static String stringA = "ABCBDAB";
	private static String stringB = "BDCABA";

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		lCS_Lenght(stringA, stringB);
		printlnArray();
		print_LCS(path, stringA, stringA.length(), stringB.length());

	}
	
	private static int lCS_Lenght(String a, String b) {
		int m = a.length();
		int n = b.length();
		
		commonLenth = new int[m + 1][n + 1];
		path = new Path[m + 1][n + 1];
		
		for(int i = 0; i <= m; i++) {
			commonLenth[i][0] = 0;
		}
		
		for (int j = 0; j<= n; j++) {
			commonLenth[0][j] = 0;
		}
		
		for(int i = 1; i <= m; i++) {
			for(int j = 1; j <= n; j++) {
				if (a.charAt(i - 1) == b.charAt(j - 1)) {
					commonLenth[i][j] = commonLenth[i - 1][j - 1] + 1;
					path[i][j] = Path.TOP_LEFT;
				} else {
					if (commonLenth[i - 1][j] >= commonLenth[i][j - 1]) {
						commonLenth[i][j] = commonLenth[i - 1][j];
						path[i][j] = Path.TOP;
					} else {
						commonLenth[i][j] = commonLenth[i][j - 1];
						path[i][j] = Path.LEFT;
					}
				}
			}
		}
		
		System.out.println("LCS_length: " + commonLenth[m][n]);
		return commonLenth[m][n];
	}
	
	
	// 从 path[][] 最后一个输出。
	private static void print_LCS(Path[][] path, String a, int i, int j) {
		if (i == 0 || j == 0) {
			return;
		}
		
		if (path[i][j] == Path.TOP_LEFT) {
			print_LCS(path, a, i - 1, j - 1);
			System.out.print(a.charAt(i - 1));
		} else {
			if (path[i][j] == Path.TOP) {
				print_LCS(path, a, i - 1, j);
			} else {
				print_LCS(path, a, i, j - 1);
			}
		}
	}
	
	private static void printlnArray() {
		int m = stringA.length();
		int n = stringB.length();
		
		for (int i = 0; i <= m; i++) {
			for (int j = 0; j<= n; j++) {
				System.out.print(commonLenth[i][j] + " ");
			}
			System.out.println();
		}
		
		System.out.println("*****************");
		Formatter formatter = new Formatter(System.out);
		for (int i = 0; i <= m; i++) {
			for (int j = 0; j<= n; j++) {
//				System.out.print(path[i][j] + " ");
				formatter.format("%-9s", path[i][j]);
			}
			System.out.println();
		}
		
	}

}