uva 531(最长公共子序列)

题意：两个人写了一些单词，要求得出一个单词集，单词集是两个人写的单词序列中的最长公共子序列。

题解：敲上最长公共子序列的模板代码后，还要递归打印出这些单词。

#include <iostream>
#include <string.h>
#include <string>
using namespace std;
const int N = 105;
string str1[N], str2[N], res[N];
int f[N][N], n, n1, n2, path[N][N], flag;

void sub_print(int a, int b) {
	if (a == 0 || b == 0)
		return;
	if (path[a][b] == 1) {
		sub_print(a - 1, b - 1);
		if (flag)
			cout << " ";
		flag = 1;
		cout << str1[a];
	}
	else if (path[a][b] == 2)
		sub_print(a - 1, b);
	else
		sub_print(a, b - 1);
}

int main() {
	while (cin >> str1[1]) {
		flag = 0;
		n1 = 1;
		while (str1[n1] != "#")
			cin >> str1[++n1];
		cin >> str2[1];
		n2 = 1;
		while (str2[n2] != "#")
			cin >> str2[++n2];
		memset(f, 0, sizeof(f));
		n1--;
		n2--;
		for (int i = 1; i <= n1; i++)
			for (int j = 1; j <= n2; j++)
				if (str1[i] == str2[j]) {
					f[i][j] = f[i - 1][j - 1] + 1;
					path[i][j] = 1;
				}
				else {
					f[i][j] = f[i - 1][j] > f[i][j - 1] ? f[i - 1][j] : f[i][j - 1];
					if (f[i][j] == f[i - 1][j])
						path[i][j] = 2;
					else
						path[i][j] = 3;
				}
		sub_print(n1, n2);
		cout << endl;
	}
	return 0;
}