Go: package main

import (
	"bufio"
	"os"
	"io"
	"strconv"
	"math"
	"fmt"
)

var (
	nstr   func() string
	stdout *bufio.Writer
)

func init() {
	nstr = newReadString(os.Stdin)
	stdout = bufio.NewWriter(os.Stdout)
}

func main() {
	defer stdout.Flush()

	n := nint()
	xList := make([]string, n)
	yList := make([]string, n)

	for i:=0;i<n ;i++  {
		xList[i] = nstr()
		yList[i] = nstr()
	}

	for i := 0; i<n	; i++  {
		fmt.Println(lcs(xList[i], yList[i]))
	}

}

func lcs(x string, y string) int{
	var m = len(x)
	var n = len(y)

	c := make([][]int, m+1)
	for i:= range c{
		c[i] = make([]int, n+1)
	}
	for i:=	1;i<=m ;i++  {
		for j:=1;j<=n ;j++  {
			if x[i-1] == y[j-1]{
				c[i][j] = c[i-1][j-1] + 1
			}else{
				c[i][j] = int(math.Max(float64(c[i-1][j]), float64(c[i][j-1])))
			}


		}
	}
	return c[m][n]

}


func newReadString(ior io.Reader) func() string {
	r := bufio.NewScanner(ior)
	r.Buffer(make([]byte, 1024), int(1e+11))
	r.Split(bufio.ScanWords)

	return func() string {
		if !r.Scan() {
			panic("Scan failed")
		}
		return r.Text()
	}
}

func nint64() int64 {
	i, err := strconv.ParseInt(nstr(), 0, 64)
	if err != nil {
		panic(err.Error())
	}
	return i
}

func nint() int {
	return int(nint64())
}

func getIntSlice(n int) []int {
	b := make([]int, n)
	for i := 0; i < n; i++ {
		b[i] = nint()
	}
	return b
}

func getStringSlice(n int) []string {
	b := make([]string, n)
	for i := 0; i < n; i++ {
		b[i] = nstr()
	}
	return b
}

func gcd(x, y int) int {
	if y == 0 {
		return x
	}
	return gcd(y, x%y)
}

func lcm(x, y int) int {
	return x * y / gcd(x, y)
}

func contains(s []int, e int) bool {
	for _, a := range s {
		if a == e {
			return true
		}
	}
	return false
}

func bin(i int, prefix bool) string {
	i64 := int64(i)

	if prefix {
		return "0b" + strconv.FormatInt(i64, 2)
	} else {
		return strconv.FormatInt(i64, 2)
	}
}

func strReverse(s string) string {
	runes := []rune(s)
	for i, j := 0, len(runes)-1; i < j; i, j = i+1, j-1 {
		runes[i], runes[j] = runes[j], runes[i]
	}

	return string(runes)
}

C++: #include <bits/stdc++.h>
using namespace std;

#define FOR(i,a,b) for (int i=(a);i<(b);i++)
#define RFOR(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define REP(i,n) for (int i=0;i<(n);i++)
#define RREP(i,n) for (int i=(n)-1;i>=0;i--)

const int MAX_L=1001;//?????????????????§??????

vector<vector<int> > DP(MAX_L, vector<int>(MAX_L, -1));
string A;//?????????????????????????????????
string B;

//A???a???????????¨????????\??????B???b???????????¨????????\??????????????§????????§?????¨????????????????????????????????????
//m?????????????????????????????±??????????????????
int dev(int a, int b){
	if(DP[a][b]<0){
		int maxi= 0;
		//???????????????????????§??????
		for(int c='A'; c<='Z'; ++c){
			int posa = A.find(c,a);
			int posb = B.find(c,b);
			if(posa>=0 && posb>=0){
				int tmp = dev(posa+1,posb+1);
				maxi = max(maxi, tmp+1);
			}
		}
		DP[a][b]=maxi;
	}
	return DP[a][b];
}

int main(){
	int q;
	cin >> q;
	vector<int> ans(q);
	REP(i,q){
		REP(k,MAX_L){
			REP(l,MAX_L){
				DP[k][l] = -1;
			}
		}
		cin>>A>>B;
		ans[i]=dev(0,0);
	}
	REP(i,q){
		cout<<ans[i]<<endl;
	}
	return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;

const int N = 1e4 + 10;
long long n, q, m, tmp;
long long dp[N][N];
string s, p;
string a1, a2;

int main() 
{
	cin >> q;
	for (int x = 0; x < q; x++) {
	cin >> a1 >> a2;
	if (a1.size() > a2.size())
		s = a1, p = a2;
	else
		p = a1, s = a2;
	n = s.size();
	m = p.size();
	
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < m; j++) {
			if(s[i] == p[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[i + 1][j + 1] << '\n';
		}
	}
	cout << dp[n][m] << '\n';
	}
	return 0;
}

C++: #include<iostream>
#include<string>
#include<algorithm>
usig 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=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 "bits/stdc++.h"
#include <unordered_set>

#define _CRT_SECURE_NO_WARNINGS

#define REP(i, n) for(decltype(n) i = 0; i < (n); i++)
#define REP2(i, x, n) for(decltype(x) i = (x); i < (n); i++)
#define REP3(i, x, n) for(decltype(x) i = (x); i <= (n); i++)
#define RREP(i, n) for (decltype(n) i = (n) - 1; i >= 0; i--)

#define ALL(a) (a).begin(),(a).end()
#define SORT(c) sort((c).begin(),(c).end())
#define DESCSORT(c) sort(c.begin(), c.end(), greater<int>())

using namespace std;

const int INF = 1000000000;
const double PI = 3.1415926535897932384626433832795;

// N, E, S, W
const int dx[4] = { -1, 0,  1,  0 };
const int dy[4] = { 0, 1,  0, -1 };

using LL = long long int;
using LD = long double;
using pii = pair<int, int>;
using pdd = pair<double, double>;
using pll = pair<LL, LL>;
using vi = vector<int>;
using vd = vector<double>;
using vvi = vector<vi>;
using vll = vector<LL>;

//==============================================
vvi dp(1050, vi(1050));

int lcs(string x, string y) {
	int ans = 0;
	int m = x.size();
	int n = y.size();

	x = ' ' + x;
	y = ' ' + y;
	REP3(i, 1, m) {
		REP3(j, 1, n) {
			if (x[i] == y[j]) {
				dp[i][j] = dp[i - 1][j - 1] + 1;
			} else {
				dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]);
			}
			ans = max(ans, dp[i][j]);
		}
	}

	return ans;
}

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

	int q;
	cin >> q;

	string str1, str2;
	REP(i, q) {
		cin >> str1 >> str2;
		cout << lcs(str1, str2) << "\n";
	}
	return 0;
}

C++: #include <iostream>
#include <algorithm>
using namespace std;

#define REP(i, n) for(int (i) = 0; (i) < (n); (i)++)

string str1, str2;
int dp[1001][1001];
int k;

int solve(int i, int j)
{
  if(dp[i][j] > 0)
    return dp[i][j];
  if(i == str1.size() || j == str2.size()){
    if(i != str1.size()){
      return solve(i + 1, k);
    }else{
      return 1;
    }
  }
  if(str1[i] == str2[j]){
    k = j + 1;
    dp[i][j] = solve(i + 1, j + 1);
    return dp[i][j] + 1;
  }else{
    return solve(i, j + 1);
  }
}

int main()
{
  int q, n, ans = 0;
  cin >> q;
  cin.ignore();
  REP(i, q){
    getline(cin, str1);
    getline(cin, str2);
    if(str1.size() < str2.size())
      swap(str1, str2);
    fill(&dp[0][0], &dp[1001][0], -1);
    REP(j, str1.size()){
      n = solve(j, 0) - 1;
      ans = (n > ans) ? n : ans;
    }
    swap(str1, str2);
    fill(&dp[0][0], &dp[1001][0], -1);
    REP(j, str1.size()){
      n = solve(j, 0) - 1;
      ans = (n > ans) ? n : ans;
    }
    cout << ans << endl;
    ans = 0;
    fill(&dp[0][0], &dp[1001][0], -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;  // X[0] に空白を挿入
  Y = ' ' + Y;  // Y[0] に空白を挿入
  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;
}