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;

#define Vi vector<int>
#define FOR(i,s,e) for (int i=s; i<e; i++)
#define ITER(v) v.begin(), v.end()

constexpr int MAX_LEN = 1'000;
int dp[MAX_LEN][MAX_LEN];

void set_val(int i, int j, int inc) {
    int val = inc;
    if (i > 0 && j > 0) {
        int tmp = dp[i-1][j-1] + inc;
        val = max(val, tmp);
    }
    if (i > 0) {
        int tmp = dp[i-1][j] + inc;
        val = max(val, tmp);
    }
    if (j > 0) {
        int tmp = dp[i][j-1] + inc;
        val = max(val, tmp);
    }
    dp[i][j] = val;
}

int lcs(const string& x, const string& y) {
    int lx = x.length();
    int ly = y.length();
    for (int i=0; i<lx; ++i) {
        bool isalreadyinc = false;
        for (int j=0; j<ly; ++j) {
            if (x[i] == y[j] && !isalreadyinc) {
                set_val(i, j, 1);
                isalreadyinc = true;
            } else {
                set_val(i, j, 0);
            }
        }
    }
    return dp[lx-1][ly-1];
}

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

    int n;
    cin >> n;

    string x, y;
    FOR(i,0,n) {
        cin >> x;
        cin >> y;
        cout << lcs(x, y) << endl;
    }

    return 0;
}

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

#define MAX 1001

using namespace std;

int lcs(string X, string Y);

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


int lcs(string X, string Y)
{
	int c[MAX][MAX] = {0};
	X = ' ' + X;
	Y = ' ' + Y;
	for (int i = 1; i < X.length(); i++)
	{
		for (int j = 1; j < Y.length(); 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]);
		}
	}
	return c[X.length()-1][Y.length()-1];
}

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 i = 0; i <= n; ++i)
    {
        c[0][i] = 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 <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;//在X[0]中插入空格
    Y = ' ' + Y;//在Y[0]中插入空格
    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<string>
using namespace std;

int main(){
  int i,j,n,c[1001][1001];
  string x,y;
  cin >> n;
  while(n>0){
    n--;
    cin >> x;
    cin >> y;

    int lenx = x.size();
    int leny = y.size();

    for(i = 1; i <= lenx; i++){
      c[i][0] = 0;
    }
    for(j = 1; j <= leny; j++){
      c[0][j] = 0;
    }
  
    for(i = 1; i <= lenx; i++){
      for(j = 1; j <= leny; 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];
	}
      }
    }
    cout << c[lenx][leny] << endl;
  }
  return 0;
}

C++: #include <algorithm>
#include <iostream>
#include <string>
using namespace std;
#define MAX 1000



int solve(string x, string y) {
  int xl = x.size();
  int yl = y.size();
  int lcs[MAX + 1][MAX + 1];

  int i, j;
  for (i = 0; i < xl; i++)
    lcs[i][0] = 0;
  for (j = 0; j < yl; j++)
    lcs[0][j] = 0;

  // shift
  x = " " + x;
  y = " " + y;

  int maxlcs = 0;
  for (i = 1; i <= xl; i++) {
    for (j = 1; j <= yl; j++) {
      if (x[i] == y[j]) {
        lcs[i][j] = lcs[i - 1][j - 1] + 1;
      } else {
        int a = lcs[i][j - 1];
        int b = lcs[i - 1][j];
        lcs[i][j] = max(a, b);
      }
      maxlcs = max(maxlcs, lcs[i][j]);
    }
  }
  return maxlcs;
}

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