请使用C语言编写用动态规划算法、递归算法求最长公共子序列的代码

动态规划算法：

#include <stdio.h>
#include <string.h>

#define MAXLEN 1000

int longest_common_subsequence(char s1[], char s2[]) {
    int m = strlen(s1), n = strlen(s2);
    int dp[MAXLEN+1][MAXLEN+1];
    int i, j;
    for (i = 0; i <= m; i++) {
        dp[i][0] = 0;
    }
    for (j = 0; j <= n; j++) {
        dp[0][j] = 0;
    }
    for (i = 1; i <= m; i++) {
        for (j = 1; j <= n; j++) {
            if (s1[i-1] == s2[j-1]) {
                dp[i][j] = dp[i-1][j-1] + 1;
            } else {
                dp[i][j] = (dp[i-1][j] > dp[i][j-1]) ? dp[i-1][j] : dp[i][j-1];
            }
        }
    }
    return dp[m][n];
}

int main() {
    char s1[MAXLEN+1], s2[MAXLEN+1];
    scanf("%s %s", s1, s2);
    int len = longest_common_subsequence(s1, s2);
    printf("%d\n", len);
    return 0;
}

递归算法：

#include <stdio.h>
#include <string.h>

int longest_common_subsequence(char s1[], char s2[], int m, int n) {
    if (m == 0 || n == 0) {
        return 0;
    }
    if (s1[m-1] == s2[n-1]) {
        return longest_common_subsequence(s1, s2, m-1, n-1) + 1;
    } else {
        int len1 = longest_common_subsequence(s1, s2, m-1, n);
        int len2 = longest_common_subsequence(s1, s2, m, n-1);
        return (len1 > len2) ? len1 : len2;
    }
}

int main() {
    char s1[MAXLEN+1], s2[MAXLEN+1];
    scanf("%s %s", s1, s2);
    int len = longest_common_subsequence(s1, s2, strlen(s1), strlen(s2));
    printf("%d\n", len);
    return 0;
}

这里使用了 MAXLEN 宏定义来指定字符串的最大长度，可以根据实际情况修改。