最长公共子序列（二维数组解决）

#include<iostream>
#include<string>
#include<vector>
using namespace std;
void print(vector<vector<int> > &vecb,string str1,int i,int j)
{
	if(i==0||j==0)
	{
		return;
	}
	if(vecb[i][j]==1)
	{
		print(vecb,str1,i-1,j-1);
		cout<<str1[i-1]<<" ";
	}
	else if(vecb[i][j]==2)
	{
	   print(vecb,str1,i-1,j);
	   }
	else
		print(vecb,str1,i,j-1);
}
int LCSXL(const string &str1,const string &str2)
{
	if(str1==""||str2=="")
		return 0;
	vector<vector<int> > veca(str1.length() + 1, vector<int>(str2.length() + 1));
	vector<vector<int> > vecb(str1.length() + 1, vector<int>(str2.length() + 1));
	int maxend=0;
	int max=0;
	int i,j;
	for (i = 0; i <= str1.length(); i++) {
		veca[i][0] = 0;
	}
	for (j = 0; j <= str2.length(); j++) {
		veca[0][j] = 0;
	}
	for (i = 1; i <= str1.length(); i++) {
		for (j = 1; j <= str2.length(); j++) {
			if (str1[i - 1] == str2[j - 1]) {
				veca[i][j] = veca[i - 1][j - 1] + 1;
				vecb[i][j]=1;
			}
			else {
				if (veca[i - 1][j] >= veca[i][j - 1])
				{
					veca[i][j] = veca[i - 1][j];
				    vecb[i][j]=2;
				}
				else
				{
					veca[i][j] = veca[i][j-1];
					vecb[i][j]=3;
				}
			}
		}
	}
	string s1=str1;
	print(vecb,str1,s1.length(),str2.length());

	return veca[i-1][j-1];
}

int main()
{
	string str1,str2;
	while(cin>>str1>>str2)
	{
		cout<<LCSXL(str1,str2)<<endl;
	}
	return 0;
}