C :

/*
 * =====================================================================================
 *
 *       Filename:  908.c
 *
 *    Description:  hahah LCS 
 *
 *        Version:  1.0
 *        Created:  2013/9/8 22:08:10
 *       Revision:  none
 *       Compiler:  gcc
 *
 *         Author:  mdk-vim.cpp-c (mdk), mengdaikun@gmail.com
 *        Company:  cjluacm-vim-mdk
 *
 * =====================================================================================
 */
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<math.h>
#define MAX 100

int dp[MAX][MAX];

int max(int a, int b)
{
    return a > b ? a : b ;
}

int main()
{
    //freopen("a.in","r",stdin);
    
    char str1[MAX],str2[MAX];
    
    int i,j;

    int len1,len2;

    while(~scanf("%s %s",str1,str2))
    {
        
        len1 = strlen(str1);
        
        len2 = strlen(str2);

        for(i = 0 ; i <= len1 ; i++)
            
            dp[0][i] = 0;

        for(j = 0 ; j <= len2 ; j++)

            dp[j][0] = 0;

        for(j = 0 ; j < len1 ; j++)
        {
            for(i = 0 ; i < len2 ; i++)
            {
                if(str1[j] == str2[i])
                    dp[i+1][j+1] = dp[i][j]+1;
                else
                    dp[i+1][j+1] = max(dp[i][j+1],dp[i+1][j]);
            }
        }

        printf("%d\n",dp[len2][len1]);
    }

    return 0;
}

Java :

import java.util.*;
import java.io.*;
import java.math.*;


public class Main{
	
	public static Scanner cin=new Scanner(System.in);
	public static String a,b;
	public static int[][] dp;
	public static int lena,lenb;
	public static void main(String []args){
		while(cin.hasNext()){
			a=cin.next();
			b=cin.next();
			lena=a.length();
			lenb=b.length();
			dp=new int[lena][lenb];
			for(int i=0;i<lena;i++){
				for(int j=0;j<lenb;j++){
					if(i==0&&j==0){
						if(a.charAt(i)==b.charAt(j)){
							dp[i][j]=1;
						}else{
							dp[i][j]=0;
						}
					}else if(i==0){
						if(a.charAt(i)==b.charAt(j)){
							dp[i][j]=1;
						}else{
							dp[i][j]=dp[i][j-1];
						}
					}else if(j==0){
						if(a.charAt(i)==b.charAt(j)){
							dp[i][j]=1;
						}else{
							dp[i][j]=dp[i-1][j];
						}
					}else{
						if(a.charAt(i)==b.charAt(j)){
							dp[i][j]=dp[i-1][j-1]+1;
						}else{
							dp[i][j]=Math.max(dp[i-1][j], dp[i][j-1]);
						}
					}
				}
			}
			System.out.println(dp[lena-1][lenb-1]);
		}
	}
}