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 <iostream>
#include <string>
#include <vector>
#include <algorithm>

constexpr int nil = -1;

class ILcs
{
public:
    using vvi = std::vector<std::vector<int>>;
    virtual int lcs() = 0;
    virtual int lcs(int i1, int i2) = 0;
};

class LcsLoop : public ILcs
{
public:

    LcsLoop(std::string str1, std::string str2)
        : str1 {" " + str1}
        , str2 {" " + str2}
        , dp {vvi(str1.size() + 1, std::vector<int>(str2.size() + 1))}
    {
        CalcLcs();
    }

    int lcs() override
    {
        return lcs(str1.size() - 1, str2.size() - 1);
    }

    int lcs(int i1, int i2) override
    {
        return dp[i1][i2];
    }

private:

    std::string str1;
    std::string str2;
    vvi         dp;
    
    void CalcLcs()
    {
        for (int i = 0; i < str1.size(); ++i)
            dp[i][0] = 0;
        for (int i = 0; i < str2.size(); ++i)
            dp[0][i] = 0;

        for (int i = 1; i < str1.size(); ++i)
        {
            for (int j = 1; j < str2.size(); ++j)
            {
                if (str1[i] == str2[j])
                    dp[i][j] = dp[i - 1][j - 1] + 1;
                else
                    dp[i][j] = std::max(dp[i][j - 1], dp[i - 1][j]);
            }
        }
    }
};

//class LcsReccursion : public ILcs
//{
//public:
//    LcsReccursion(const std::string& str1, const std::string& str2)
//        : str1 {str1}
//        , str2 {str2}
//        , dp {vvi(str1.size(), std::vector<int>(str2.size(), nil))}
//    {}
//
//    int lcs() override
//    {
//        return lcs(str1.size() - 1, str2.size() - 1);
//    }
//
//    int lcs(int i1, int i2) override
//    {
//        if (dp[i1][i2] != nil)
//            return dp[i1][i2];
//
//        if (i1 == 0 || i2 == 0)
//        {
//            if (i1 == 0 && i2 == 0) return dp[i1][i2] = (str1[i1] == str2[i2]);
//            else if (i1 == 0)       return dp[i1][i2] = std::max(lcs(i1, i2 - 1), (str1[i1] == str2[i2] ? 1 : 0));
//            else                    return dp[i1][i2] = std::max(lcs(i1 - 1, i2), (str1[i1] == str2[i2] ? 1 : 0));
//        }
//
//        dp[i1][i2] = std::max(lcs(i1 - 1, i2), lcs(i1, i2 - 1))
//            + (str1[i1] == str2[i2]);
//        return dp[i1][i2];
//    }
//
//private:
//
//    std::string str1;
//    std::string str2;
//    vvi         dp;
//};

void solve()
{
    using namespace std;

    int n;
    cin >> n;

    string s1, s2;

    for (int i = 0; i < n; ++i)
    {
        cin >> s1 >> s2;
        LcsLoop lcs {s1, s2};
        //LcsReccursion lcs {s1, s2};
        cout << lcs.lcs() << ((i != n - 1) ? "\n" : "");
    }
}

int main()
{
    solve();
    return 0;
}

C++: #include<iostream>
#include<algorithm>
using namespace std;
int dp[1001][1001];
string s,t;
int n,m,a,ans;
int main(){
  cin>>a;
  for(int b=0;b<a;b++){
    cin>>s>>t;
    for(int i=0;i<=1000;i++)
      for(int j=0;j<=1000;j++)
	dp[i][j]=0;
    m=s.size();
    n=t.size();
    ans=0;
    for(int i=1;i<=m;i++){
      for(int j=1;j<=n;j++){
	if(s[i-1]==t[j-1]){
	  dp[i][j]=dp[i-1][j-1]+1;
	}else{
	  dp[i][j]=max(dp[i-1][j],dp[i][j-1]);
	}
      }
    }  
    cout<<dp[m][n]<<endl;
  }
  return 0;
}

C++: #include<iostream>
#include<string>
#include<algorithm>
using namespace std;
static const int N = 1000;

int lcs(string X,string Y){
  int c[N+1][N+1];
  int m = X.size();
  int n = Y.size();
  int maxl = 0;
  X = ' ' + X;
  Y = ' '+Y;
  for(int i = 0;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]);
      }
      maxl = max(maxl, c[i][j]);
    }
  }
  return  maxl;
}

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 <iostream>
#include <algorithm>

using namespace std;

int main() {
  int Tc; cin >> Tc;
  
  while(Tc--) {
    string s, t; cin >> s >> t;
    
    int dp[1001][1001] = {{}};
    
    int const N = s.size(), M = t.size();
    
    for(int i=0; i<N; i++) {
      for(int j=0; j<M; j++) {
        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]);
        }
      }
    }
    
    cout << dp[N][M] << endl;
  }
  
  return 0;
}