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>
#include<cmath>
#include<vector>
#include<string>

using namespace std;
#define ML 1000

inline int comp_char(char a,char b) { if(a==b) return 1;else return 0;}


int longest_cmmsubseq(string &xcomp,string &ycomp,vector<vector<int>> &memo){
  int ysize=ycomp.size();
  int xsize=xcomp.size();
  int max=0;
  for(int i=0;i<xsize;i++){
    if(ycomp.at(0)==xcomp.at(i)){
      while(i<xsize){ memo.at(i).at(0)=1; i++;}
      continue;
    }
    else memo.at(i).at(0)=0;
  }
  for(int j=0;j<ysize;j++){
    if(ycomp.at(j)==xcomp.at(0)){
      while(j<ysize){ memo.at(0).at(j)=1; j++;}
      continue;
    }
    else memo.at(0).at(j)=0;
  }

  for(int j=1;j<ysize;j++){
    for(int i=1;i<xsize;i++){
      max=memo.at(i-1).at(j-1)+comp_char(xcomp.at(i),ycomp.at(j));
      if(max<memo.at(i-1).at(j)) max=memo.at(i-1).at(j);
      if(max<memo.at(i).at(j-1)) max=memo.at(i).at(j-1);
      memo.at(i).at(j)=max;
      max=0;
    }
  }
  return memo.at(xsize-1).at(ysize-1);
}

int main(void){

  int size;
  cin>>size;

  vector<vector<int>> memo(ML,vector<int>(ML));
  string xcomp,ycomp;
  for(int i=0;i<size;i++){
    cin>>xcomp>>ycomp;
    cout<<longest_cmmsubseq(xcomp,ycomp,memo)<<endl;
  }
}

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

using namespace std;                                         
                                                             
//L[i][j] X[0]..X[i]??¨X[0]..Y[j]???LCS                        
int L[1000][1000]={};                                        
int main(){
  int testnum;
  cin>>testnum;                                              
  for(int t=0;t<testnum;++t){                                
    string X,Y;                                              
    cin>>X>>Y;
    
    for(int i=1;i<=X.length();++i){                          
      for(int j=1;j<=Y.length();++j){                        
        if(X[i-1]==Y[j-1])
          L[i][j] = 1 + L[i-1][j-1];                         
        else
          L[i][j] = max(L[i][j-1],L[i-1][j]);
      }
    }

    cout << L[X.length()][Y.length()] << endl;
  }
 
  return 0;
}

C++: #include<iostream>
#include<string>
#include<algorithm>
using namespace std;
static const int N = 1000; // 読み取り専用（書き換え不可)

int lcs(string X, string Y){
    int c[N+1][N+1];
    int m = X.size();
    int n = Y.size();
    int maxv = 0;
    X = ' ' + X; //X[0]に空白を挿入
    Y = ' ' + Y; //Y[0]に空白を挿入
    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]);
            }
         maxv = max(maxv,c[i][j]);   
        } 
    }
    return maxv;
}

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>
using namespace std;
#define int long long

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

  int n; cin >> n;
  while( n-- ) {
    string s,t; cin >> s >> t;
    int N = max(s.size(),t.size());
    vector< vector<int> > dp(N+1,vector<int>(N+1,0));
    for(int i = 0; i < s.size(); i++){
      for(int j = 0; j < t.size(); j++){
        if(s[i] == t[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[s.size()][t.size()] << endl;
  }

  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef pair<ll,ll> pl;
typedef vector<pl> vp;
#define fore(i,a,b) for(ll i=(a);i<=(b);++i)
#define rep(i,n) fore(i,0,(n)-1)
#define rfore(i,a,b) for(ll i=(b);i>=(a);--i)
#define rrep(i,n) rfore(i,0,(n)-1)
#define all(x) (x).begin(),(x).end()
const ll INF=1001001001;
const ll LINF=1001001001001001001;
const ll D4[]={0,1,0,-1,0};
const ll D8[]={0,1,1,0,-1,-1,1,-1,0};
template<class T>
bool chmax(T &a,const T &b){if(a<b){a=b;return 1;}return 0;}
template<class T>
bool chmin(T &a,const T &b){if(b<a){a=b;return 1;}return 0;}

void solve(){
    ll n;cin>>n;
    while(n--){
        string s,t;cin>>s>>t;
        ll l1=s.size(),l2=t.size();
        vvl dp(l1+1,vl(l2+1));
        rep(i,l1)rep(j,l2){
            dp[i+1][j+1]=max(dp[i][j+1],dp[i+1][j]);
            if(s[i]==t[j])dp[i+1][j+1]=dp[i][j]+1;
        }
        cout<<dp[l1][l2]<<endl;
    }
}

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

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;
}