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;
using ll =long long;
typedef pair<int,int> P;
#define SORT(a) sort((a).begin(),(a).end())
#define rSORT(a) reverse((a).begin(),(a).end())
#define For(i, a, b)    for(int i = (a) ; i < (b) ; ++i)
#define rep(i, n)       For(i, 0, n)
#define debug(x)  cerr << #x << " = " << (x) << endl;
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
//Write From this Line

int main()
{
	int q;
	cin >> q;
	while(q--){
		string a, b;
		cin >> a >> b;
		int dp[1010][1010];
		dp[0][0] = 0;
		rep(i,a.size()){
			rep(j,b.size()){
				if(a[i] == b[j]){
					dp[i+1][j+1] = dp[i][j] + 1;
				} else {
					dp[i+1][j+1] = max(dp[i+1][j], dp[i][j+1]);
				}
			}
		}
		cout << dp[a.size()][b.size()] << endl;
	}
}

C++: 
#include<algorithm>
#include<iostream>

using namespace std;

const int MAX = 1000;
int ary[MAX][MAX];

int getVal(int n, int m) {

	if (m >= 0 && n >= 0 && m < MAX && n < MAX) {
		return ary[n][m];
	}
	else {
		return 0;
	}
}

int LCS(string s1, string s2) {

	int m, n;
	m = s1.length();
	n = s2.length();
	const char* c1 = s1.c_str();
	const char* c2 = s2.c_str();

	for (int i = 0;i < n;i++) {
		for (int k = 0;k < m;k++) {

			if (c1[k] != c2[i]) {
				ary[i][k] = max(getVal(i - 1, k), getVal(i, k - 1));
			}
			else if (c1[k] == c2[i]) {
				ary[i][k] = getVal(i - 1, k- 1) + 1;
			}
		}
	}

	return ary[n - 1][m - 1];
}


int main() {


	int num;
	cin >> num;

	string str1, str2;

	for (int i = 0;i < num;i++) {
		cin >> str1 >> str2;

		cout << LCS(str1, str2) << 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;//??¨X[0]????????\?????????
	Y=' '+Y;//??¨Y[0]????????\?????????
	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]);
			}
			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 <string>
#include <vector>


constexpr int MAXLENGTH = 1000;
int C[MAXLENGTH + 1][MAXLENGTH + 1];
int lcs(std::string lhs, std::string rhs) {
    int lnum = lhs.length();
    int rnum = rhs.length();
    for (int i = 0; i <= lnum; i++) {
        C[i][0] = 0;
    }
    for (int i = 0; i <= rnum; i++) {
        C[0][i] = 0;
    }
    for (int il = 1; il <= lnum; il++) {
        for (int ir = 1; ir <= rnum; ir++) {
            if (lhs[il-1] == rhs[ir-1]) {
                C[il][ir] = C[il - 1][ir - 1] + 1;
            }else if(C[il - 1][ir] >= C[il][ir - 1]) {
                C[il][ir] = C[il-1][ir];
            }else{
                C[il][ir] = C[il][ir - 1];
            }
        }
    }
    return C[lnum][rnum];
}

int main() {
    int n;
    std::cin >> n;
    for (int i = 0; i < n; i++) {
        std::string l, r;
        std::cin >> l;
        std::cin >> r;
        std::cout << lcs(l, r) << std::endl;
    }
}

C++: #include <iostream>
#include <vector>
#include <string>
#include <cmath>
#include <set>
#include <algorithm>
#include <array>
#include <complex>
#include <utility>
#include <map>
#include <inttypes.h>

int LCS(std::string s,std::string t){
    int n,m,c[1001][1001]={0};
    n=s.size();
    m=t.size();
    int maxlen=0;
    for(int i=1;i<=n;i++){
        c[i][0]=0; 
    }
    for(int i=1;i<=m;i++){
        c[0][i]=0;
    }
    for(int i=1;i<=n;i++){
        for(int j=1;j<=m;j++){
            if(s[i]==t[j]){
                c[i][j]=c[i-1][j-1]+1;
            }else{
                c[i][j]=std::max(c[i-1][j],c[i][j-1]);
            }
            maxlen=std::max(c[i][j],maxlen);
        }
    }
    return maxlen;
}
int main(){
	int N;
    
    std::cin >> N;
    std::string s1,s2;
    for(int i=0;i<N;i++){
        std::cin >> s1 >> s2;
        std::cout << LCS(s1,s2) <<std::endl;
    }
        
    
    return 0;
}

C++: #include<iostream>
#include<algorithm>
#include<vector>
#include<string>

const int s=1001;

using namespace std;

int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);

	int q;
	static unsigned int dp[s][s] = {0};
	
	dp[0][0] = 0; dp[0][1] = 0; dp[1][0] = 0;

	cin >> q;
	for(int k=0; k < q; k++){
		string X,Y;
		cin >> X >> Y;
		int i,j;
		for(i=0;i<X.size();i++){
			for(j=0;j<Y.size();j++){
				if(X[i] == Y[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[i][j] << "\n";
	}
	return 0;
}