Go: package main

/*
最長共通部分列
*/

import (
	"bufio"
	"bytes"
	"fmt"
	"log"
	"os"
	"strconv"
	"strings"
)

func larger(l, r int) int {
	if l > r {
		return l
	}
	return r
}

var memo [1001][1001]int

func countLCS(x, y string) int {
	x = " " + x
	y = " " + y
	max := 0
	for xi := 1; xi < len(x); xi++ {
		for yi := 1; yi < len(y); yi++ {
			if x[xi] == y[yi] {
				memo[xi][yi] = memo[xi-1][yi-1] + 1
			} else {
				memo[xi][yi] = larger(memo[xi-1][yi], memo[xi][yi-1])
			}
			max = larger(max, memo[xi][yi])
		}
	}
	return max
}

func main() {
	scanner := makeScanner(1024)
	q := eGetInt(scanner)
	for i := 0; i < q; i++ {
		x := eGetLine(scanner)
		y := eGetLine(scanner)
		fmt.Println(countLCS(x, y))
	}
}

////////////////////////////////////////////////////////////////////////////////
// ライブラリ
////////////////////////////////////////////////////////////////////////////////
func makeScanner(maxByte int) *bufio.Scanner {
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Buffer(make([]uint8, 0, 8192), maxByte)
	return scanner
}
func makeWordScanner() *bufio.Scanner {
	scanner := makeScanner(8192)
	scanner.Split(bufio.ScanWords)
	return scanner
}
func eGetLine(r *bufio.Scanner) string {
	if r.Scan() {
		return r.Text()
	}
	err := r.Err()
	if err != nil {
		log.Fatal(err)
	}
	// EOF
	return ""
}
func eGetInt(r *bufio.Scanner) int {
	line := eGetLine(r)
	return eAtoi(line)
}
func eGetFields(r *bufio.Scanner) []string {
	line := eGetLine(r)
	return strings.Fields(line)
}
func eGetInts(r *bufio.Scanner) []int {
	fields := eGetFields(r)
	ints := make([]int, len(fields))
	for i := 0; i < len(ints); i++ {
		ints[i] = eAtoi(fields[i])
	}
	return ints
}
func eGetChars(r *bufio.Scanner) []string {
	line := eGetLine(r)
	return strings.Split(line, "")
}
func eAtoi(s string) int {
	n, err := strconv.Atoi(s)
	if err != nil {
		log.Fatal(err)
	}
	return n
}

type ints []int

func (s ints) String() string {
	var buf bytes.Buffer
	buf.WriteString("[")
	sep := ""
	for _, v := range s {
		buf.WriteString(fmt.Sprintf("%s%d", sep, v))
		sep = ", "
	}
	buf.WriteString("]")
	return buf.String()
}

func reverse(a ints) ints {
	r := make(ints, len(a))
	for i := 0; i < len(a); i++ {
		r[i] = a[len(a)-1-i]
	}
	return r
}
func max(a ints) (int, bool) {
	if len(a) == 0 {
		return 0, false
	}
	m := a[0]
	for _, e := range a {
		if e > m {
			m = e
		}
	}
	return m, true
}
func min(a []int) int {
	m := a[0]
	for _, v := range a {
		if v < m {
			m = v
		}
	}
	return m
}

func sum(a ints) int {
	if len(a) == 0 {
		return 0
	}
	sum := 0
	for _, e := range a {
		sum += e
	}
	return sum
}
func find(n int, a ints) int {
	for i, v := range a {
		if n == v {
			return i
		}
	}
	return -1
}

C++: #include<iostream>
#include<map>
#include<vector>
#include<algorithm>
#include<cmath>
#include<climits>
#include<ctime>
#include<cstring>
#include<numeric>

#define ALL(v) (v).begin(),(v).end()
#define REP(i,p,n) for(int i=p;i<(int)(n);++i)
#define rep(i,n) REP(i,0,n)
#define dump(a) (cerr << #a << "=" << (a) << endl)
#define DUMP(list) cout << "{ "; for(auto nth : list){ cout << nth << " "; } cout << "}" << endl;

using namespace std;

const int INF = 100000000;

int main() {
	int N;
	cin >> N;
	rep(i, N) {
		string s1, s2;
		cin >> s1 >> s2;
		int n = s1.size();
		int m = s2.size();
		vector<vector<int>> dp(n+1, vector<int>(m+1, 0));
		dp[0][0] = 0;
		for(int i = 1; i <= n; ++i) {
			for(int j = 1; j <= m; ++j) {
				if(s1[i-1] == s2[j-1]) {
					dp[i][j] = dp[i-1][j-1] + 1;
				} else {
					dp[i][j] = max(dp[i-1][j], dp[i][j-1]);
				}	
			}
		}
		cout << dp[n][m] << endl;
	}
	return 0;
}

C++: #include <iostream>
#include <cstdio>
#include <climits>
#include <cmath>
#include <algorithm>
#include <utility>
#include <vector>
#include <string>

#define MAX 200000
#define INFTY 1<<30

using namespace std;

static const int N = 1000;

int lcs(string X, string Y)
{
  int dp[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++) dp[i][0] = 0;
  for(int j = 0; j < n; j++) dp[0][j] = 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
        dp[i][j] = max(dp[i-1][j],dp[i][j-1]);
      maxl = max(maxl,dp[i][j]);
    }
  }
  return maxl;
}

int main()
{
  int n; cin >> n;
  string s1, s2;
  for(int i = 0; i < n; i++)
  {
    cin >> s1 >> s2;
    cout << lcs(s1,s2) << endl;
  }
  return 0;
}

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

int main(){
  int n;
  char x[1001],y[1001];
  int dp[1002][1002];
  


  //load n;
  cin >>n;
  for(int i=0;i<n;i++){
    //initialize
    for(int i=0;i<1002;i++){
      for(int j=0;j<1002;j++){
	dp[i][j]=0; 
      }
    }
    //load string
    scanf("%s",x);
    scanf("%s",y);
    //dp
    for(int j=0;j<strlen(x);j++){
      for(int k=0;k<strlen(y);k++){
	if(x[j]==y[k]){
	  dp[j+1][k+1]=dp[j][k]+1;
	}

	else{
 
	  if(dp[j][k+1]>dp[j+1][k]){
	    dp[j+1][k+1]=dp[j][k+1];
	  }

	  else{
	    dp[j+1][k+1]=dp[j+1][k];
	  }
	}
      }
    }

    //print
    cout <<dp[strlen(x)][strlen(y)]<<endl;
  }



  return 0;
}

C++: #include <iostream>
#include <algorithm>
#include <string>
using namespace std;
static const int N = 1000;
int C[N + 1][N + 1];

int lcs(string X, string Y)
{
	int m = X.size();
	int n = Y.size();
	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;

	int maxl = 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;
	}
}

C++: #include <map>
#include <set>
#include <list>
#include <cmath>
#include <queue>
#include <stack>
#include <cstdio>
#include <string>
#include <vector>
#include <complex>
#include <cstdlib>
#include <cstring>
#include <numeric>
#include <sstream>
#include <iostream>
#include <algorithm>
#include <functional>
 
#define mp       make_pair
#define pb       push_back
#define all(x)   (x).begin(),(x).end()
#define rep(i,n) for(int i=0;i<(n);i++)
 
using namespace std;
 
typedef    long long          ll;
typedef    unsigned long long ull;
typedef    vector<bool>       vb;
typedef    vector<int>        vi;
typedef    vector<vb>         vvb;
typedef    vector<vi>         vvi;
typedef    pair<int,int>      pii;
 
const int INF=1<<29;
const double EPS=1e-9;
 
const int dx[]={1,0,-1,0},dy[]={0,-1,0,1};


int main(int argc, char const *argv[]) {
	int N;
	cin >> N;
	for (int i = 0; i < N; ++i) {
		string s1;
		string s2;
		cin >> s1 >> s2;
		int dp[1000][1000] = {{0}};
		for (int i = 0; i < s1.size(); ++i) {
			if (s1[i] == s2[0]) {
				dp[i][0] = 1;
			}
		}
		for (int i = 0; i < s2.size(); ++i) {
			if (s1[0] == s2[i]) {
				dp[0][1] = 1;
			}
		}
		for (int i = 1; i < s1.size(); ++i) {
			for (int j = 1; j < s2.size(); ++j) {
				if (s1[i] == s2[j]) {
					dp[i][j] = dp[i - 1][j - 1] + 1;
				} else {
					dp[i][j] = std::max(dp[i - 1][j], dp[i][j - 1]);
				}
			}
		}
		cout << dp[s1.size() - 1][s2.size() - 1] << endl;
	}	

	return 0;
}