04_最长公共子串长度

一、测试输入：

LOOP
HELLOWORLD

二、经转移公式推导： 

三、测试程序

/*
 *    最长公共子串长度
 *
 */

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

#define MAX(a, b)    (a)>(b) ? (a):(b)

int get_lcs_len(unsigned char *m, unsigned char *n)
{
    int lm = strlen(m);
    int ln = strlen(n);
    int max = 0;
    int i = 1;
    int j = 1;
    
    int (*dp)[ln] = (int (*)[ln])malloc(sizeof(int)*lm*ln);
    memset(dp, 0, sizeof(int)*lm*ln);

    for (; i<lm; i++)
        for (j=1; j<ln; j++) {
            if (m[i] == n[j])
                max = MAX(max, dp[i][j]=dp[i-1][j-1]+1);        
            else
                dp[i][j] = 0;
        }

    for (i=0; i<lm; i++) {
        for (j=0; j<ln; j++)
            printf("%d ", dp[i][j]);
        puts("");
    }
    free(dp);

    return max;
}

int main()
{
    unsigned char str1[1024] = {' '};
    unsigned char str2[1024] = {' '};

    while (~scanf("%s%s", str1+1, str2+1))
        printf("%d
", get_lcs_len(str1, str2));

    return 0;
}