LintCode-Longest Common Subsequence

Given two strings, find the longest comment subsequence (LCS).

Your code should return the length of LCS.

Example

For "ABCD" and "EDCA", the LCS is "A" (or D or C), return 1

For "ABCD" and "EACB", the LCS is "AC", return 2

Solution:

public class Solution {
    /**
     * @param A, B: Two strings.
     * @return: The length of longest common subsequence of A and B.
     */
    public int longestCommonSubsequence(String A, String B) {
        int lenA = A.length(), lenB = B.length();
        if (lenA==0 || lenB == 0) return 0;

        int[][] lcs = new int[lenA+1][lenB+1];
        for (int i=0;i<=lenA;i++) lcs[i][0] = 0;
        for (int i=0;i<=lenB;i++) lcs[0][i] = 0;

        for (int i=1;i<=lenA;i++)
            for (int j=1;j<=lenB;j++){
                lcs[i][j] = Math.max(lcs[i-1][j], lcs[i][j-1]);
                if (A.charAt(i-1) == B.charAt(j-1) && lcs[i][j]<lcs[i-1][j-1]+1)
                lcs[i][j] = lcs[i-1][j-1]+1;
            }

        return lcs[lenA][lenB];
    }
}