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 <string>
using namespace std;
const static int N = 1000;
int dp[N + 1][N + 1];

int lcs(string X, string Y) {
	int max = 0;
	int m = X.size();
	int n  = Y.size();
	X = ' ' + X;
	Y = ' ' + Y;

	for (int i = 1; i <= m; i++)
		dp[i][0] = 0;
	for (int i = 1; i <= n; i++)
		dp[0][i] = 0;

	for (int i = 1; i <= m; i++) {
		for ( int j = 1; j <= n; j++) {
			if (X[i] == Y[j])
				dp[i][j] = dp[i - 1][j - 1] + 1;
			else {
				if (dp[i - 1][j] > dp[i][j - 1])
					dp[i][j] = dp[i - 1][j];
				else
					dp[i][j] = dp[i][j - 1];
			}

			max = (max < dp[i][j]) ? dp[i][j] : max;
		}
	}

	return max;
}

int main(int argc, char const *argv[]) {
	int n;
	cin >> n;


	for (int i = 0; i < n; i++) {
		string X, Y;
		cin >> X >> Y;

		cout << lcs(X, Y) << endl;
	}

	return 0;
}

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

const int INF = 1e8;

int main(){ 
  int Q; cin >> Q;

  for(int query = 0; query<Q; query++){
    string S, T; cin >> S >> T;

    //dp[i][j]: S[i],T[j]まででの最長共通部分列
    vector<vector<int>> dp(1010, vector<int>(1010, 0));
    
    for(int i=0; i<S.length(); i++){
      for(int j=0; j<T.length(); 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.length()][T.length()] << endl;
  }
}

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

#define MAX_N 1000
#define MAX_M 1000

string s, t;
int dp[MAX_N + 1][MAX_M + 1];

void solve(){
	for(int i = 0; i < s.length(); i++){
		for(int j = 0; j < t.length(); j++){
			if(s[i] == t[j]){
				dp[i + 1][j + 1];
					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.length()][t.length()] << endl;
}

int main(){
	int n;
	cin >> n;
	for(int i = 0; i < n; i++){
		cin >> s >> t;
		solve();
	}
}

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]+1,dp[i][j-1],dp[i-1][j]});
					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;
}

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)
{
  for (int i = 0; i < cnrvsStrX.size(); ++i)
  {
    const int nMAXNX = cnrvsStrX[i].size();
    const int nMAXNY = cnrvsStrY[i].size();
    vector<vector<int>> vvnLcsDP(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<iostream>
#include<string>
#include<vector>
using namespace std;

int main(){
  int q;
  cin>>q;
  while(q--){
    string X,Y;
    cin>>X>>Y;
    vector<vector<int> > v(X.size()+1,vector<int>(Y.size()+1,0));
    for(int i=0;i<X.size();i++){
      for(int j=0;j<Y.size();j++){
	if(X[i] == Y[j]){
	  v[i+1][j+1] = v[i][j]+1;
	}else{
	  v[i+1][j+1] = max(v[i+1][j],v[i][j+1]);
	}
      }
    }
    cout<<v[X.size()][Y.size()]<<endl;
  }
  return 0;
}

C++: #include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cassert>
#include <string>
#include <cstring>
#include <vector>
#include <list>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <algorithm>

using namespace std;

// ---------------------
// repetition
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)

// debug
#define dump(x)  cerr << #x << " = " << (x) << endl;
#define debug(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << endl;

// ---------------------
#define INF 922337203685477580
typedef long long ll;

int dp[1010][1010];

int main() {
  int q;
  cin >> q;
  REP(loop, q) {
    char S[1000], T[1000];
    cin >> S >> T;

    REP(i, strlen(S)) {
      REP(j, strlen(T)) {
        dp[i][j] = 0;
      }
    }
    for (int i = 0; i < strlen(S); i++) {
      for (int j = 0; j < strlen(T); 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[strlen(S)][strlen(T)] << endl;
  }

  return 0;
}