带输出:
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 1005;
char a[N], b[N];
int dp[N][N], index, res;
void lcs(char a[], char b[]){
int len1 = strlen(a);
int len2 = strlen(b);
index = res = 0;
memset(dp, 0, sizeof(dp));
for(int i=1; i<=len1; i++)
for(int j=1; j<=len2; j++){
if(a[i-1]==b[j-1]) dp[i][j] = dp[i-1][j-1] + 1;
if(res <= dp[i][j]){
res = dp[i][j];
index = i;
}
}
printf("%d\n", res);
}
void print(char a[], char b[]){
for(int i=index-res; i<index; i++)
printf("%c", a[i]);
puts("");
}
int main(){
while(~scanf("%s %s", a, b)){
lcs(a, b);
print(a, b);
}
}