Go: package main

/*
最長共通部分列
*/

import (
	"bufio"
	"bytes"
	"fmt"
	"log"
	"os"
	"strconv"
	"strings"
)

func larger(l, r int) int {
	if l > r {
		return l
	}
	return r
}

var memo [1001][1001]int

func countLCS(x, y string) int {
	x = " " + x
	y = " " + y
	max := 0
	for xi := 1; xi < len(x); xi++ {
		for yi := 1; yi < len(y); yi++ {
			if x[xi] == y[yi] {
				memo[xi][yi] = memo[xi-1][yi-1] + 1
			} else {
				memo[xi][yi] = larger(memo[xi-1][yi], memo[xi][yi-1])
			}
			max = larger(max, memo[xi][yi])
		}
	}
	return max
}

func main() {
	scanner := makeScanner(1024)
	q := eGetInt(scanner)
	for i := 0; i < q; i++ {
		x := eGetLine(scanner)
		y := eGetLine(scanner)
		fmt.Println(countLCS(x, y))
	}
}

////////////////////////////////////////////////////////////////////////////////
// ライブラリ
////////////////////////////////////////////////////////////////////////////////
func makeScanner(maxByte int) *bufio.Scanner {
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Buffer(make([]uint8, 0, 8192), maxByte)
	return scanner
}
func makeWordScanner() *bufio.Scanner {
	scanner := makeScanner(8192)
	scanner.Split(bufio.ScanWords)
	return scanner
}
func eGetLine(r *bufio.Scanner) string {
	if r.Scan() {
		return r.Text()
	}
	err := r.Err()
	if err != nil {
		log.Fatal(err)
	}
	// EOF
	return ""
}
func eGetInt(r *bufio.Scanner) int {
	line := eGetLine(r)
	return eAtoi(line)
}
func eGetFields(r *bufio.Scanner) []string {
	line := eGetLine(r)
	return strings.Fields(line)
}
func eGetInts(r *bufio.Scanner) []int {
	fields := eGetFields(r)
	ints := make([]int, len(fields))
	for i := 0; i < len(ints); i++ {
		ints[i] = eAtoi(fields[i])
	}
	return ints
}
func eGetChars(r *bufio.Scanner) []string {
	line := eGetLine(r)
	return strings.Split(line, "")
}
func eAtoi(s string) int {
	n, err := strconv.Atoi(s)
	if err != nil {
		log.Fatal(err)
	}
	return n
}

type ints []int

func (s ints) String() string {
	var buf bytes.Buffer
	buf.WriteString("[")
	sep := ""
	for _, v := range s {
		buf.WriteString(fmt.Sprintf("%s%d", sep, v))
		sep = ", "
	}
	buf.WriteString("]")
	return buf.String()
}

func reverse(a ints) ints {
	r := make(ints, len(a))
	for i := 0; i < len(a); i++ {
		r[i] = a[len(a)-1-i]
	}
	return r
}
func max(a ints) (int, bool) {
	if len(a) == 0 {
		return 0, false
	}
	m := a[0]
	for _, e := range a {
		if e > m {
			m = e
		}
	}
	return m, true
}
func min(a []int) int {
	m := a[0]
	for _, v := range a {
		if v < m {
			m = v
		}
	}
	return m
}

func sum(a ints) int {
	if len(a) == 0 {
		return 0
	}
	sum := 0
	for _, e := range a {
		sum += e
	}
	return sum
}
func find(n int, a ints) int {
	for i, v := range a {
		if n == v {
			return i
		}
	}
	return -1
}

C++: #include<bits/stdc++.h>
using namespace std;
static const int N=1001;
int lcs(string X,string Y){
  int c[N+1][N+1];
  int m=X.size();
  int n=Y.size();

  int max1=0;
  X=' '+X;
  Y=' '+Y;

  for(int i=1;i<=m;i++){
    c[i][0]=0;
  }
  for(int j=1;j<=n;j++){
    c[0][j]=0;
  }

  for(int i=1;i<=m;i++){
    for(int j=1;j<=n;j++){
      if(X[i]==Y[j]){
	c[i][j]=c[i-1][j-1]+1;
      }
      else {
	c[i][j]=max(c[i-1][j],c[i][j-1]);
      }
      max1=max(max1,c[i][j]);
    }
  }
  return max1;
}

int main(){
  string s1,s2;
  int n;
  cin>>n;
  for(int i=0;i<n;i++){
    cin>>s1>>s2;
    cout<<lcs(s1,s2)<<endl;
  }
  return 0;
}

C++: #include <bits/stdc++.h>
#ifdef _DEBUG
#include "debug.hpp"
#else
#define debug(...)
#endif
#define REP(i, m, n) for(int (i) = (m); (i) < (n); ++i)
#define rep(i, n) REP(i, 0, n)
using namespace std;
typedef long long ll;
typedef pair<ll, ll> P;
const int INF = 1e9 + 7;
const ll LINF = 1LL << 60;
template<class T, class U> inline bool chmax(T &a, const U &b) { if(a < b) { a = b; return true; } return false; }
template<class T, class U> inline bool chmin(T &a, const U &b) { if(a > b) { a = b; return true; } return false; }

int q;

int main() {
  cin.tie(0); ios::sync_with_stdio(false);
  cin >> q;
  rep(qi,q) {
    string x, y;
    cin >> x >> y;
    int n = x.size(), m = y.size();
    vector<vector<int>> dp(n+10, vector<int>(m+10, 0));
    rep(i,n) rep(j,m) {
      if(x[i] == y[j]) chmax(dp[i+1][j+1], dp[i][j]+1);
      else {
        chmax(dp[i+1][j+1], max(dp[i+1][j], dp[i][j+1]));
      }
    }
    cout << dp[n][m] << '\n';
  }
  return 0;
}

C++: #include "bits/stdc++.h"
#include "math.h"
 
using namespace std;
typedef long long ll;
typedef vector<ll> vll;
typedef vector<vll> vvll;
typedef vector<bool> vb;
typedef vector<vb> vvb;
typedef vector<int> vin;
typedef vector<vin> vvin;
typedef pair<ll,ll> P;
typedef vector<P> vp;
#define rep(i,a,b) for(ll i=(a);i<(b);++i)
#define drep(i,a,b) for(ll i=(a);i>=(b);--i)
#define SIZE(a) int((a).size())
const int MOD=1e9+7;

int main(){
  ll u;cin>>u;
  rep(k,0,u){

  string x,y;cin>>x>>y;
  ll n=x.size(),m=y.size();
  vvll dp(n+1,vll(m+1,0));
  
  rep(i,0,n){
    rep(j,0,m){
      if(x[i]==y[j])dp[i+1][j+1]=max(dp[i][j]+1,max(dp[i][j+1],dp[i+1][j]));
      else{dp[i+1][j+1]=max(dp[i][j+1],dp[i+1][j]);}
    }
  }
  
  cout<<dp[n][m]<<endl;
  }
}

C++: #include <iostream>
#include <string>
#include <algorithm>
using namespace std;
int c[1010][1010];
int lcs(string x,string y){
    int m = x.size();
    int n = y.size();
    int maxl;
    for (int i=1; i<=m; i++) {
        c[i][0] = 0;
    }
    for(int j=1;j<=n;j++){
        c[0][j] = 0;
    }
    x = ' '+x;
    y = ' '+y;
    for(int i=1;i<=m;i++){
        for(int j=1;j<=n;j++){
            if(x[i]==y[j]){
                c[i][j] = c[i-1][j-1] + 1;
            }
            else c[i][j] = max(c[i-1][j], c[i][j-1]);
            maxl = max(maxl, c[i][j]);
        }
        
    }
    return maxl;
}
int main(){
    int q;
    string x;
    string y;
    scanf("%d",&q);
    for (int i=0; i<q; i++) {
        cin>>x>>y;
        cout<<lcs(x, y)<<endl;
    }
    return 0;
}

C++: #include<iostream>
#include<cstdio>
#include<cstdlib>
#include<vector>
#include<string>
#include<cstring>
#include<algorithm>

using namespace std;

void commonSeq(){
    string seq1, seq2;
    cin >> seq1;
    cin >> seq2;
    int nrow = seq1.length() + 1;
    int ncol = seq2.length() + 1;
    vector< vector<int> > dpmat;
    dpmat = vector< vector<int> >(nrow, vector<int>(ncol, 0));
    for(int i = 0; i < nrow; i++){
        dpmat[i][0] = 0;
    }
    for(int j = 0; j < ncol; j++){
        dpmat[0][j] = 0;
    }

    for(int i = 1; i < nrow; i++){
        for(int j = 1; j < ncol; j++){
            dpmat[i][j] = max(max(dpmat[i-1][j-1] + (seq1[i-1] == seq2[j-1]), dpmat[i-1][j]), dpmat[i][j-1]);
        }
    }
    printf("%d\n", dpmat[nrow-1][ncol-1]);
}

int main(){
    int n; 
    cin >> n;
    for(int i = 0; i < n; i++){
        commonSeq();
    }
    return 0;
}

C++: #include "bits/stdc++.h"
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
#define rep(i,n) for(ll i=0;i<(ll)(n);i++)
#define all(a)  (a).begin(),(a).end()
#define pb push_back
#define INF 99999999

#define MAX_S 2000
#define MAX_T 2000

template<typename T> int lcs(T s,T t){
    int lens=s.size();
    int lent=t.size();
    int dp[MAX_S+1][MAX_T+1]={};

    rep(i,lens){
        rep(j,lent){
            if(s[i]==t[j])  dp[i+1][j+1] = dp[i][j]+1;
            else            dp[i+1][j+1] = max(dp[i][j+1],dp[i+1][j]);
        }
    }
    return dp[lens][lent];
}

int main(){
    int n;
    cin>>n;
    rep(i,n){
        string s,t;
        cin>>s>>t;
        cout<<lcs(s,t)<<endl;
    }
}