Common Subsequence

#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
int dp[1000][1000];
int main(){
    char s1[1000],s2[1000];
    char t;
    while(~scanf("%s%s",s1,s2)){
            memset(dp,0,sizeof(dp));
       int    n1 = strlen(s1);
       int    n2 = strlen(s2);
          for(int i = 1 ; i <= n1;i++){
            for(int j = 1;j <= n2; 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]);
            }
          }
          printf("%d\n",dp[n1][n2]);
    }
    return 0;
}