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 <iostream>
using namespace std;

#define MAX 1024

int LCS[MAX][MAX];

void ini(){
}
int solve(string s1,string s2){
  if(s1.length() > s2.length())
	swap(s1,s2);
  for(int i=1;i<=s1.length();i++){
    for(int j=1;j<=s2.length();j++){
      if(s1[i-1]==s2[j-1])
	LCS[i][j]=LCS[i-1][j-1]+1;
      else
	LCS[i][j]=max(LCS[i][j-1],LCS[i-1][j]);
    }
  }
  return LCS[s1.length()][s2.length()];
}


int main(){
  string s1, s2;
  int n;
  cin >> n;
  for(int i=0;i<n;i++){
    for(int i=0;i<MAX;i++){
      for(int j=0;j<MAX;j++){
        LCS[i][j] = 0;
      }
    }
    cin>>s1>>s2;
    cout<<solve(s1,s2)<<endl;
    /*
    for(int i=0;i<=s1.length();i++){
      for(int j=0;j<=s2.length();j++){
	cout << LCS[i][j] << "  " ;
      }
      cout << endl;
    }*/
  }

}

C++: #include <cstdio>
#include <iostream>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <string>
#include <vector>
#include <list>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <bitset>
#include <numeric>
#include <climits>
#include <cfloat>
#include <functional>
#include <cctype>

using namespace std;

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

string X, Y;

void solve(int x_size, int y_size)
{
	vector< vector<int> > dp(x_size + 1, vector<int>(y_size + 1));

	for(int i = 0; i < x_size; ++i) {
		for(int 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[x_size][y_size] << endl;
}

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

	int n;
	cin >> n;
	REP(i, n) {
		cin >> X >> Y;
		solve(X.size(), Y.size());
	}
	return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<int, int>;

#define rep(i, n) for (int i = 0; i < n; ++i)
#pragma region Debug
template <typename T>
void view(const std::vector<T> &v)
{
    for (const auto &e : v)
    {
        std::cout << e << " ";
    }
    std::cout << std::endl;
}
template <typename T>
void view(const std::vector<std::vector<T>> &vv)
{
    for (const auto &v : vv)
    {
        view(v);
    }
}
#pragma endregion
#pragma region chminmax
template <typename T>
inline bool chmin(T &a, T b)
{
    if (a > b)
    {
        a = b;
        return true;
    }
    return false;
}
template <typename T>
inline bool chmax(T &a, T b)
{
    if (a < b)
    {
        a = b;
        return true;
    }
    return false;
}
#pragma endregion

int main()
{
    int q;
    cin >> q;
    rep(d, q)
    {
        string s, t;
        cin >> s >> t;
        vector<vector<int>> dp(s.size() + 1, vector<int>(t.size() + 1));

        rep(i, s.size()) rep(j, t.size())
        {

            chmax(dp[i + 1][j + 1], dp[i][j] + (s[i] == t[j]));
            chmax(dp[i + 1][j + 1], dp[i + 1][j]);
            chmax(dp[i + 1][j + 1], dp[i][j + 1]);
        }
        cout << dp[s.size()][t.size()] << endl;
    }
    return 0;
}

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

void fnInput(vector<string>& rvsStrX, vector<string>& rvsStrY)
{
  int nMaxSiz;
  cin >> nMaxSiz;
  rvsStrX.resize(nMaxSiz);
  rvsStrY.resize(nMaxSiz);

  for (int i = 0; i < nMaxSiz; ++i)
  {
    cin >> rvsStrX[i] >> rvsStrY[i];
    rvsStrX[i] = ' ' + rvsStrX[i];
    rvsStrY[i] = ' ' + rvsStrY[i];
  }
}

int fnLngCmnSubseq(const vector<string>& cnrvsStrX, const vector<string>& cnrvsStrY)
{
  vector<vector<int>> vvnLcsDP;
  for (int i = 0; i < cnrvsStrX.size(); ++i)
  {
    const int nMAXNX = cnrvsStrX[i].size();
    const int nMAXNY = cnrvsStrY[i].size();

    vvnLcsDP.clear();
    vvnLcsDP.resize(nMAXNX, vector<int>(nMAXNY, 0));

    for (int nx = 1; nx < nMAXNX; ++nx)
      for (int ny = 1; ny < nMAXNY; ++ny)
        if (cnrvsStrX[i][nx] == cnrvsStrY[i][ny])
          vvnLcsDP[nx][ny] = vvnLcsDP[nx - 1][ny - 1] + 1;
        else
          vvnLcsDP[nx][ny] = max(vvnLcsDP[nx - 1][ny], vvnLcsDP[nx][ny - 1]);

    cout << vvnLcsDP[nMAXNX - 1][nMAXNY - 1] << endl;
  }
}

int main()
{
  cin.tie(0);
  ios::sync_with_stdio(false);
  vector<string> vsStrX, vsStrY;

  fnInput(vsStrX, vsStrY);
  fnLngCmnSubseq(vsStrX, vsStrY);
  return 0;
}

C++: #include "bits/stdc++.h"
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
#define rep(i,n) for(ll i=0;i<(ll)(n);i++)
#define all(a)  (a).begin(),(a).end()
#define pb push_back
#define INF (1e9+1)
//#define INF (1LL<<59)


int main(){
    int n;
    cin>>n;
    rep(i,n){
        string s,t;
        cin>>s>>t;
        
        
        int dp[1001][1001]={};
        
        rep(i,s.size()){
            rep(j,t.size()){
                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[s.size()][t.size()]<<endl;
    }
}

C++: #include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <string>
#include <cmath>
#include <vector>
typedef long long ll;
using namespace std;

int lcs(string x,string y){
  int xl=x.length(),yl=y.length();
  int dp[1001][1001],i,j;

  memset(dp,0,sizeof(dp));

  for(i=1;i<=xl;i++){
    for(j=1;j<=yl;j++){
      if(x[i-1]==y[j-1]){
        dp[i][j]=dp[i-1][j-1]+1;
      }
      else{
        dp[i][j]=max(dp[i-1][j],dp[i][j-1]);
      }
    }
  }

  return dp[xl][yl];
}

int main(void){
  int q,i;
  string x,y;
  
  cin>>q;
  for(i=0;i<q;i++){
    cin>>x>>y;
    cout<<lcs(x,y)<<endl;
  }

  return 0;
}