sicily LCS

直接用递归做了一下，超时了，可能要再加上记忆化搜索？不会...

然后再用动态规划就过了...

http://soj.sysu.edu.cn/show_problem.php?pid=1002&cid=1762

//直接递归，tle
#include <iostream>
#include <cstdio>
#include <cstring>

using namespace std;

char s1[1001];
char s2[1001];

int LCS(char s1[], char s2[], int len1, int len2)
{
    if(len1 == 0 || len2 == 0)
        return 0;
    if(s1[len1-1] == s2[len2-1])
        return 1+LCS(s1, s2, len1-1, len2-1);
    else
        return max(LCS(s1, s2, len1-1, len2), LCS(s1, s2, len1, len2-1));
}

int main()
{
    while(cin >> s1 >> s2)
    {
        int len1 = strlen(s1);
        int len2 = strlen(s2);
        cout << LCS(s1, s2, len1, len2) << endl;
    }
    return 0;
}

//动规，思路是一样的
#include <iostream>
#include <cstring>
#include <cstdio>

using namespace std;

char s1[1001];
char s2[1001];
int dp[1001][1001];

int LCS(char s1[], char s2[])
{
    int len1 = strlen(s1);
    int len2 = strlen(s2);
    memset(dp, 0, sizeof(dp));
    
    for(int i=1; i<=len1; i++)
    {
        for(int j=1; j<=len2; j++)
        {
            if(s1[i-1] == s2[j-1])
                dp[i][j] = dp[i-1][j-1] + 1;
            else
                dp[i][j] = max(dp[i-1][j], dp[i][j-1]);
        }
    }
    return dp[len1][len2];
}

int main()
{
    while(cin >> s1 >> s2)
    {
        cout << LCS(s1, s2) << endl;
    }
    return 0;
}