有关最长公共子序列算法只是一个简单的问题。 我这样做，你需要生成序列的部分如下：
Just a quick question about the longest Common subsequence algorithm. I have done the part where you need to generate the subsequence as follow:
public int[][] lcsLength(char[] input1, char[] input2) { int[][] opt = new int[M][N]; for (int i = 1; i < input1.length; i++) { for (int j = 1; j < input2.length; j++) { if (input1[i] == input2[j]) { opt[i][j] = opt[i - 1][j - 1] + 1; } else { opt[i][j] = Math.max(opt[i][j - 1], opt[i - 1][j]); } } } return opt; }
和printDiff功能如下：
and the printDiff function as follow:
private static void printDiff(int[][] opt,String x,String y,int i, int j) { if(i>0 &&j>0 && x.charAt(i-1)==y.charAt(j-1)){ printDiff(i-1,j-1); System.out.println(x.charAt(i-1)); } else{ if(j>0&&(i==0||opt[i][j-1]>=opt[i-1][j])){ printDiff(i-1,j-1); System.out.println("-"+y.charAt(j-1)); } else if(i>0&&(j==0|| opt[i][j-1]<=opt[i-1][j])){ printDiff(i-1,j-1); System.out.println(x.charAt(i-1)); } } }
然后，如果我用这个作为参数：
And then if I use this as parameters:
String input1="ABCDE" String input2="ACDC" int i=input1.length() int j=input2.length()
产生选择矩阵lcsLength（）后，我想，竟被printdiff给我：
after generating the opt matrix with lcsLength() I wish that printdiff woul give me :
ABCDE- A-CD-C
而是我得到的：
but instead I get:
ABCDE- ABCD-C这是我做错了什么会帮助我很多的任何想法
any ideas on what I did wrong would help me a lot
谢谢 洛朗
推荐答案不知道，如果它是一个相关的问题，但我觉得你的LCS code应该是：
Don't know if it's a related issue, but I think your LCS code should be:
public int[][] lcsLength(char[] input1, char[] input2) { int[][] opt = new int[input1.length+1][input2.length+1]; for (int i = 1; i <= input1.length; i++) { for (int j = 1; j <= input2.length; j++) { if (input1[i-1] == input2[j-1]) { opt[i][j] = opt[i - 1][j - 1] + 1; } else { opt[i][j] = Math.max(opt[i][j - 1], opt[i - 1][j]); } } } return opt; }