LCS最长公共子串

#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
int dp[5050][5050]; 
char a[5050],b[5050];
int main(){
    freopen("lcslength.in","r",stdin);
    freopen("lcslength.out","w",stdout);
    int l1,l2,i,j;
    scanf("%s%s",a+1,b+1);
    l1=strlen(a+1);l2=strlen(b+1);
    for(i=1;i<l1;i++){
        for(j=1;j<l2;j++){
            if(a[i]==b[j])dp[i][j]=dp[i-1][j-1]+1;
            else dp[i][j]=max(dp[i-1][j],dp[i][j-1]);
        }
    }
    printf("%d",dp[l1-1][l2-1]);
    return 0;
}