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 <algorithm>
#include <string.h>
#include <queue>

using namespace std;

#define ARRAY_MAX 150
#define MAX 1000 + 1

char X[MAX];
char Y[MAX];

#pragma region 暴力递归
int FindLCS1(char x[], int i, char y[], int j)
{
	int l1 = strlen(x);
	int l2 = strlen(y);

	// 到索引末尾结束
	if (i >= l1 || j >= l2) return 0;

	if (x[i] == y[j])
		return 1 + FindLCS1(x, i + 1, y, j + 1);
	else
		return max(FindLCS1(x, i, y, j + 1), FindLCS1(x, i + 1, y, j));
}

int LongestCommonSubsequence1(char x[], char y[])
{
	return FindLCS1(x, 0, y, 0);
}
#pragma endregion

#pragma region 记忆搜索
int memory[MAX][MAX];
int FindLCS2(char x[], int i, char y[], int j)
{
	int l1 = strlen(x);
	int l2 = strlen(y);

	// 到索引末尾结束
	if (i >= l1 || j >= l2) return 0;

	if (memory[i][j] != -1) return memory[i][j];

	if (x[i] == y[j])
		return memory[i][j] = 1 + FindLCS2(x, i + 1, y, j + 1);
	else
		return memory[i][j] = max(FindLCS2(x, i, y, j + 1), FindLCS2(x, i + 1, y, j));
}

int LongestCommonSubsequence2(char x[], char y[])
{
	int l1 = strlen(x);
	int l2 = strlen(y);
	for (int i = 0; i < l1; ++i)
		for (int j = 0; j < l2; ++j)
			memory[i][j] = -1;

	return FindLCS2(x, 0, y, 0);
}
#pragma endregion

#pragma region 动态规划
int dp[MAX][MAX];

int LongestCommonSubsequence3(char x[], char y[])
{
	int l1 = strlen(x);
	int l2 = strlen(y);
	int size = sizeof(int) * (MAX) * (MAX);
	memset(dp, 0, size);
	for (int i = l1 - 1; i >= 0; --i)
		for (int j = l2 - 1; j >= 0; --j)
		{
			if (x[i] == y[j])
				dp[i][j] = 1 + dp[i + 1][j + 1];
			else
				dp[i][j] = max(dp[i + 1][j], dp[i][j + 1]);
		}

	return dp[0][0];
}
#pragma endregion

int main()
{
	int q; cin >> q;
	queue<int> result;
	for (int i = 0; i < q; ++i)
	{
		cin >> X;
		cin >> Y;
		result.push(LongestCommonSubsequence3(X, Y));
	}

	while (!result.empty())
	{
		cout << result.front() << endl;
		result.pop();
	}

	return 0;
}

C++: #include <iostream>
#include <stdio.h>
#include <string>
#include <cmath>

#define MAX_LENGTH 1000
#define NIL -1
using namespace std;
//think easy make easy

int q;//num of datasets
string X;
string Y;
char map[MAX_LENGTH+1][MAX_LENGTH+1];

int findMaxLength(int x,int y){//x:Xの終端.y:Yの終端(0オリジン)
	int val;

	if(x < 0 || y < 0) return 0;

	if(map[x][y] == NIL){
		if(X.at(x) == Y.at(y)){
			val = findMaxLength(x-1,y-1) +1;
		}else{
			val = max(findMaxLength(x-1,y),findMaxLength(x,y-1));
		}
		map[x][y] = val;//メモ
		return val;
	}else return map[x][y];
}

int main(){
	
	scanf("%d",&q);

	for(int i=0;i<q;i++){
		cin >>X; cin >> Y;
		for(int i=0;i<X.size();i++){
			for(int j=0;j<Y.size();j++){
				map[i][j] = NIL;
			}
		}
	
		cout <<findMaxLength(X.size()-1,Y.size()-1) <<endl;
	}

	return 0;
}

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

using namespace std;



int n;
string a, b;
string x[1000], y[1000];




int main(){
  cin >> n;
  while(n != 0){
    n = n -1;
    int longest[1000][1000];
    cin >> a;
    cin >> b;
    a = ' ' + a;
    b = ' ' + b;
    int mm = 0;
    
   for(int i = 1; i <= a.size(); ++i){
     longest[i][0] = 0;
    }
   for(int j = 1; j <= b.size(); ++j){
     longest[0][j] = 0;
   }
    for(int i = 1; i <= a.size(); ++i){
      for(int j = 1; j <= b.size(); ++j){
        
        
        if(a[i] == b[j]){
          longest[i][j] = 1 + longest[i-1][j - 1];
        }
        else{
          longest[i][j] = max(longest[i][j-1], longest[i-1][j]);
        }
        mm = max(mm, longest[i-1][j-1]);
      }
    }
    //cout << a[1] << endl;
    cout << mm << endl;
  }
}

C++: #include<bits/stdc++.h>
#define rep(i,n)for(int i=0;i<n;i++)
using namespace std;

int dp[1001][1001];
char x[1001], y[1001];
int main() {
	int q; scanf("%d", &q);
	rep(i, q) {
		scanf("%s%s", x, y);
		rep(i, 1000)rep(j, 1000) {
			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]);
		}
		printf("%d\n", dp[1000][1000]);
	}
}

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

template<class T> inline void chmax(T& a, T b) { if (a < b) a = b; }
template<class T> inline void chmin(T& a, T b) { if (a > b) a = b; }


namespace Lcs
{

	int exec()
	{
		string S, T; cin >> S >> T;
		vector<vector<int>> dp(S.size() + 1, vector<int>(T.size() + 1, 0));
		for (int s = 0; s < S.size(); ++s) {
			for (int t = 0; t < T.size(); ++t) {
				if (S[s] == T[t]) dp[s + 1][t + 1] = dp[s][t] + 1;
				chmax(dp[s + 1][t + 1], dp[s + 1][t]);
				chmax(dp[s + 1][t + 1], dp[s][t + 1]);
			}
		}
		return dp[S.size()][T.size()];
	}
}

int main()
{
	int Q; cin >> Q;
	vector<int> anss(Q);
	for (int i = 0; i < Q; ++i) {
		anss[i] = Lcs::exec();
	}
	for (int i = 0; i < Q; ++i) {
		cout << anss[i] << endl;;
	}
}

C++: #if 0

#endif

#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;

int Q;
int L[1000+10][1000+10];

int main() {
  cin >> Q;
  string X, Y;
  for (int i = 0; i < Q; i++) {
    for (int j = 0; j < 1000+10; j++) {
      L[0][j] = 0; L[j][0] = 0;
    }
    cin >> X >> Y;
    for (int x = 1; x <= X.length(); x++) {
      for (int y = 1; y <= Y.length(); y++) {
        if (X[x-1] == Y[y-1])
          L[x][y] = L[x-1][y-1]+1;
        else
          L[x][y] = max(L[x-1][y], L[x][y-1]);
      }
    }

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