//15.4最长公共子序列
#include <iostream>
#include <string>
using namespace std;

int c[8][7];
int b[8][7];
#define x 8
#define y 7
void Lcs_Length(char s1[x],char s2[y])//求解最长公共序列
{
	int i,j;
	for(i=1;i<x;++i)
		c[i][0]=0;
	for(j=0;j<y;++j)
		c[0][j]=0;
	for(i=1;i<x;++i)
		for(j=1;j<y;++j)
		{
			if(s1[i]==s2[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;
				}
		}
}

void Print_Lcs(int b[][7],string s1,int i,int j)//递归输出最长公共序列
{
	if(i==0||j==0)
		return;
	if(b[i][j]==1)
	{
		Print_Lcs(b,s1,i-1,j-1);
		cout<<s1[i];
	}
	else
		if(b[i][j]==2)
			Print_Lcs(b,s1,i-1,j);
		else
			Print_Lcs(b,s1,i,j-1);
}

void main()
{
	char s1[x]={' ','A','B','C','B','D','A','B'},s2[y]={' ','B','D','C','A','B','A'};//第一个字符为空字符
	Lcs_Length(s1,s2);
	Print_Lcs(b,s1,7,6);
	cout<<endl;
}