Go: package main

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

// I/O
type Scanner struct {
	sc *bufio.Scanner
}

func NewScanner() *Scanner {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	sc.Buffer(make([]byte, 1024), int(1e+9))
	return &Scanner{sc}
}

func (s *Scanner) nextStr() string {
	s.sc.Scan()
	return s.sc.Text()
}

func (s *Scanner) nextInt() int {
	i, e := strconv.Atoi(s.nextStr())
	if e != nil {
		panic(e)
	}
	return i
}

func (s *Scanner) nextFloat() float64 {
	f, e := strconv.ParseFloat(s.nextStr(), 64)
	if e != nil {
		panic(e)
	}
	return f
}

func (s *Scanner) nextRuneSlice() []rune {
	return []rune(s.nextStr())
}

func (s *Scanner) nextIntSlice(n int) []int {
	res := make([]int, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextInt()
	}
	return res
}

func (s *Scanner) nextFloatSlice(n int) []float64 {
	res := make([]float64, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextFloat()
	}
	return res
}

// Arithmetic
func max(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m < i {
			m = i
		}
	}
	return m
}

func min(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m > i {
			m = i
		}
	}
	return m
}

func abs(x int) int {
	if x > 0 {
		return x
	}
	return -x
}

func pow(x, y int) int {
	res := 1
	for i := 0; i < y; i++ {
		res *= x
	}
	return res
}

func ceil(a, b int) int {
	if a%b == 0 {
		return a / b
	} else {
		return a/b + 1
	}
}

// Sort
type RuneSlice []rune

func (a RuneSlice) Len() int           { return len(a) }
func (a RuneSlice) Less(i, j int) bool { return a[i] < a[j] }
func (a RuneSlice) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }

// Main
func main() {
	sc := NewScanner()
	wtr := bufio.NewWriter(os.Stdout)
	Q := sc.nextInt()
	for q := 0; q < Q; q++ {
		X, Y := sc.nextStr(), sc.nextStr()
		xLen, yLen := len(X), len(Y)
		dp := make([][]int, xLen+1)
		for i := 0; i <= xLen; i++ {
			dp[i] = make([]int, yLen+1)
		}
		for x := 0; x <= xLen; x++ {
			for y := 0; y <= yLen; y++ {
				if x == 0 || y == 0 {
					dp[x][y] = 0
				} else if X[x-1] == Y[y-1] {
					dp[x][y] = dp[x-1][y-1] + 1
				} else {
					dp[x][y] = max(dp[x-1][y], dp[x][y-1])
				}
			}
		}
		fmt.Fprintln(wtr, dp[xLen][yLen])
	}

	wtr.Flush()
}

C++: #include "bits/stdc++.h"
#define REP(i, m, n) for(long long i = m; i < n; ++i)
#define CO(n) cout << n << endl
using namespace std;
typedef long long ll;
typedef pair<int, int> P;

int q;
string X[150], Y[150];
int dp[1001][1001];
//dp[i][j] Xのi文字目までとYのj文字目まででできるLSCの長さ

int main()
{
    ios::sync_with_stdio(false);
    cin >> q;
    REP(n,0,q) cin >> X[n] >> Y[n];
    REP(n,0,q){
        int lx = X[n].size(); int ly = Y[n].size();
        //dpテーブル初期化
        REP(i,0,lx+1) dp[i][0] = 0;
        REP(j,0,ly+1) dp[0][j] = 0;
        //dp
        REP(i,0,lx){
            REP(j,0,ly){
                if (X[n][i]==Y[n][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]);
            }
        }
        CO(dp[lx][ly]);
    }
    return 0;
}

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

using namespace std;

#define STRING_MAX 1000

int lcs(string X,string Y)
{
	int m = X.size();
	int n = Y.size();
	int c[STRING_MAX + 1][STRING_MAX + 1];
	int maxl = 0;

	X = ' ' + X;
	Y = ' ' + Y;


	for (int i = 1; i <= m; i++) {
		c[i][0] = 0;
	}
	
	for (int i = 1; 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[i]) {
				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(void)
{
	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;
	Y = ' ' + Y;
	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;
		cin >> s2;
		cout << lcs(s1, s2) << endl;
	}
	return 0;
}

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

int main(){
  int n,b[1100][1100];
  string s1,s2;
  cin>>n;
  for(int i=0;i<n;i++){
    cin>>s1>>s2;
    for(int j=0;j<=s1.size()+1;j++)b[j][0]=0;
    for(int j=0;j<=s2.size()+1;j++)b[0][j]=0;
    for(int j=1;j<=s1.size();j++){
      for(int k=1;k<=s2.size();k++){
	if(s1[j-1]==s2[k-1])b[j][k]=b[j-1][k-1]+1;
	else if(b[j][k-1]>b[j-1][k])b[j][k]=b[j][k-1];
	else b[j][k]=b[j-1][k];
      }
    }
    cout<<b[s1.size()][s2.size()]<<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;  // 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]);
      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;//??¨X[0]????????\?????????
	Y=' '+Y;//??¨Y[0]????????\?????????
	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 <iostream>
#include <string>

int max(int a, int b, int c);

int main(){
    int n;
    std::cin >> n;
    std::string str1;
    std::string str2;
    for(int i=0;i<n;i++){
        std::cin >> str1;
        std::cin >> str2;
        int size1 = str1.size();
        int size2 = str2.size();
        int dp[size1+1][size2+1];
        dp[0][0] = 0;
        for(int j=0;j<=size1;j++){
            dp[j][0] = 0;
        }
        for(int j=0;j<=size2;j++){
            dp[0][j] = 0;
        }

        for(int j=1;j<=size1;j++){
            for(int k=1;k<=size2;k++){
                dp[j][k] = max(dp[j-1][k],dp[j-1][k-1],dp[j][k-1]);
                if(str1[j]==str2[k]) dp[j][k]++;
            }
        }

        std::cout << dp[size1][size2] << std::endl;
    }
    return 0;
}

int max(int a, int b, int c){
    if(a>b){
        if(a>c){
            return a;
        }else{
            return c;
        }
    }else{
        if(b>c){
            return b;
        }else{
            return c;
        }
    }
}