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<stdio.h>
//#include<cstdlib>
#include<cstring>

#define MAX_LEN 1000

int c[MAX_LEN+1][MAX_LEN+1]; // length of longest common subsequence

void p(){
    printf("\ntest\n");
}

int max(int a, int b){
    return a > b ? a : b;
}

int LCS(char *s1, char *s2){
    int i, j,   l, m;
    l = strlen(s1);
    m = strlen(s2);
    //printf("l:%d m:%d", l, m);
    
    for (i = 0; i < l; i++) {
        c[i][0] = 0;
     }
    
    for (j = 0; j < m; j++) {
        c[0][j] = 0;
    }
    
    
    for (i = 1; i < l+1; i++) {
        for (j = 1; j < m+1; j++) {
            if (s1[i-1] == s2[j-1]) {
                c[i][j] = c[i-1][j-1] + 1;
            }else{
                c[i][j] = max(c[i][j-1], c[i-1][j]);
            }
            //printf("c[%d][%d]:%d\n", i, j, c[i][j]);
        }
    }
    
    
    return c[l][m];
}

int main(){
    int i, n;
    char s1[MAX_LEN+1], s2[MAX_LEN+1];
    
    scanf("%d", &n);
    for (i = 0; i < n; i++) {
        scanf(" %s", s1);
        scanf(" %s", s2);
        //printf("%s\n%s\n", s1, s2);
        printf("%d\n", LCS(s1, s2));
    }
    
    return 0;
}

C++: #include<stdio.h>
#include<string.h>
#include<iostream>
#include<algorithm>
using namespace std;
int p[1001][1001]={0};
int main(){
int i,j,q,e,l,z,m,u,n;
char s[2001],c[2001];
cin>>q;
for(e=0;e<q;e++){
scanf("%s %s",s,c);
l=strlen(s);
z=strlen(c);

for(i=0;i<=l;i++){
	for(j=0;j<=z;j++){
		p[i][j]=0;
	}
}
n=0;
for(i=1;i<=z;i++){
	for(j=1;j<=l;j++){
		if(c[i-1]==s[j-1])p[j][i]=p[j-1][i-1]+1;
		else p[j][i]=p[j][i-1];
	}
}
cout<<p[l][z]<<endl;
}
return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
using lint = int64_t;
#define rep(i, n) for(int i=0; i<(n); ++i)
#define all(v)    begin(v), end(v)
#define in        []{lint n; cin>>n; return n;}()


#define LCS longest_common_subsequence
int longest_common_subsequence( const string S, const string T ) {
    vector<vector<int>> dp( S.size()+1, vector<int>(T.size()+1, 0) );

    rep( s, S.size() ) {
    rep( t, T.size() ) {
        dp[s+1][t+1] = S[s] == T[t] ?
            dp[s][t] + 1 :
            max( dp[s][t+1], dp[s+1][t] );
    }
    }

    return dp[S.size()][T.size()];
}

int main() { cin.tie(0); ios::sync_with_stdio(false);
    int N = in;
    rep( _, N ) {
        string S, T; cin >> S >> T;
        cout << LCS( S, T ) << "\n";
    }
}

C++: #include <iostream>
#include <climits>
#include <string>
using namespace std;
const int MAXSEQ = 1000;
const int INFY = -INT_MAX;

string X, Y;

int max(int m, int n){
    int max = INFY;
    printf("\n");
    return max;
}
int LSCLength(void){
    int m = X.size();
    int n = Y.size();
    int c[m+1][n+1];
    for (int i = 0; i <= m; i++){
        c[i][0] = 0;
    }
    for (int j = 0; j <= n; j++){
        c[0][j] = 0;
    }
    /*
    for (int i = 0; i <= m; i++){
        for (int j = 0; j <= m; j++){
        */
    /*
    if (m > n){
        cout << "will change X =" <<  X << endl;
        swap(m, n);
        swap(X, Y);
        cout << "changed X =" <<  X << endl;
    }*/
    for (int i = 1; i <= m; i++){
        for (int j = 1; j <= n; j++){
            if (X[i-1] == Y[j-1]){
                c[i][j] = c[i-1][j-1] + 1;
            }else if (c[i-1][j] >= c[i][j-1]){
                c[i][j] = c[i-1][j];
            }else{
                c[i][j] = c[i][j-1];
            }
        }
    }
    int max = INFY;
    //printf("\n");
    /*
    for (int i = 0; i <= m; i++){
        for (int j = 0; j <= n; j++){
            printf("%d ", c[i][j]);
        if (max < c[m][i]) max = c[i][j];
        }
        printf("\n");
    }
    */
    for (int j = 1; j <= n; j++){
        if (max < c[m][j]) max = c[m][j];
    }
    return max;
}

int main(int argc, char* argv[]) {
    int n;
    cin >> n;
    for (int i = 0; i < n; i++){
        cin >> X >> Y;
        cout << LSCLength() << endl;
    }
    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define FOR(I,A,B) for(ll I = (A); I < (B); ++I)
#define POSL(x,v) (lower_bound(x.begin(),x.end(),v)-x.begin()) //xi>=v
#define POSU(x,v) (upper_bound(x.begin(),x.end(),v)-x.begin()) //xi>v
#define NUM(x,v) (POSU(x,v)-POSL(x,v))
const ll INF=1e9+7;
const ll N = 1002;
const ll M = 21;
ll q,dp[N][N];
string x,y;
vector <ll> ans;

int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);
	cin>>q;
	FOR(k,0,q){
		cin>>x>>y;
		FOR(i,0,x.size()+1){
			FOR(j,0,y.size()+1){
				dp[i][j]=0;
			}
		}
		FOR(i,0,x.size()+1){
			FOR(j,0,y.size()+1){
				if(i==0||j==0)dp[i][j]=0;
				else{
					if(x[i]==y[j])dp[i][j] = max(dp[i-1][j]+1,dp[i][j-1]+1);
					else dp[i][j] = max(dp[i-1][j],dp[i][j-1]);
				} 
			}
		}
		ans.push_back(dp[x.size()][y.size()]);
	}
	FOR(i,0,ans.size()){
		cout<<ans[i]<<endl;
	}
	return 0;
}