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++: #define _CRT_SECURE_NO_WARNINGS
#include <cstdio>
#include <cstdlib>
#include <string>
#include <iostream>
#include <queue>

using namespace std;

const char *X, *Y;
int X_length, Y_length;
bool alreadySeenTable[256];
int table_lcs[1001][1001];

int lcs(int x_begin, int y_begin) {
	int i, j, to;
	int max = 0;
	int v_lcs;
	
	if (table_lcs[x_begin][y_begin] != -1) {
		return table_lcs[x_begin][y_begin];
	}
	
	for (i = 0; i < 256; i++) {
		alreadySeenTable[i] = false;
	}
	i = x_begin;
	j = y_begin;
	to = Y_length-1;
	while(i <= X_length-1) {
		bool found = false;
		while (j <= to) {
			if (X[i] == Y[j]) {
				v_lcs = lcs(i + 1, j + 1) + 1;
				if (v_lcs > max) {
					max = v_lcs;
				}
				found = true;
				break;
			}
			else {
				j++;
			}
		}
		if (found == false) {
			i++;
			j = y_begin;
		}
		else {
			i++;
			to = j - 1;
			j = y_begin;
		}
	}
	return table_lcs[x_begin][y_begin] = max;
}

int main() {

	int N;
	cin >> N;
	string stringX, stringY;

	for (int i = 1; i <= N; i++) {
		for (int i = 0; i < 1001; i++) {
			for (int j = 0; j < 1001; j++) {
				table_lcs[i][j] = -1;
			}
		}
		cin >> stringX >> stringY;
		X = stringX.c_str();
		X_length = stringX.size();
		Y = stringY.c_str();
		Y_length = stringY.size();
		printf("%d\n", lcs(0, 0));
	}
	return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define MAX 2000
#define NOTFOUND -1
int Max = 0;
// nまでの文字列をいくつか選んで最長共通部を作ったときの長さ
//int dp[MAX];

bool 
IsInTargetString(string strFind, string strTgt)
{
    int idx;
    string strTmp = strTgt;

    for (int i = 0; i < strFind.size(); i++)
    {
        idx = strTgt.find(strFind[i]);
        if (idx != string::npos) {
            strTmp = strTgt.substr(idx+1);
            // cout << "idx = " << idx << " strFind = " << strFind
            // << " strTmp = " << strTmp <<  "\n";
        } else {
            return false;
        }
        strTgt = strTmp;
    }
    //cout <<  "\n";
    return true;
}

int
SearchCommonSubsequence(string strSet1, string strSet2)
{
    //vector<vector<bool>> dp(MAX, vector<bool>(MAX));

    // dp[i+1][j+1] = strSet1のi 文字目までとstrSet2のj文字目まででの LCS の長さ
    vector<vector<int>> dp(MAX, vector<int>(MAX));
    dp[0][0] = 0;
    string strRes = "";


    for (int i = 0; i < strSet1.size(); i++)
    {
        for (int j = 0; j < strSet2.size(); j++)
        {
            if(strSet1[i] == strSet2[j]) {
                dp[i+1][j+1] = max({dp[i][j] + 1,dp[i+1][j], dp[i][j+1]});
            } else {
                dp[i+1][j+1] = max(dp[i+1][j], dp[i][j+1]);
            }
        }
    }
        
    // for(int i=0; i<strSet1.size(); i++) {
    //     string strTmp = strRes;
    //     strTmp += strSet1[i];

    //     //if(strSet2.find(strTmp) != string::npos) {
    //     if(IsInTargetString(strTmp, strSet2)) {
    //         // 見つかった場合は更新a
    //         strRes = strTmp;
    //     } else {
    //         // 見つからなかった場合はそのまま
    //     }
    //     dp[i] = strRes.size();
    //     //cout << strRes << ", " << strSet1[i] << "\n";
    // }

    //auto itr = std::max_element(dp.begin(), dp.end());
    //return *itr;
    return dp[strSet1.size()][strSet2.size()];
}

int main()
{
    string strSet1, strSet2;
    int n;

    cin >> n;
    for (int i = 0; i < n; i++)
    {
        cin >> strSet1 >> strSet2;

        if(strSet1.size() > strSet2.size()) swap(strSet1, strSet2);
        cout << SearchCommonSubsequence(strSet1, strSet2) << "\n";
    }    
    return 0;
}

C++: #include <iostream>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <algorithm>
#include <functional>
#include <vector>
#include <list>
#include <queue>
#include <deque>
#include <stack>
#include <map>
#include <set>
#include <bitset>
#include <tuple>
#include <cassert>
#include <exception>
#include <iomanip>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll,ll> P;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<string> vs;
typedef vector<P> vp;
#define rep(i,a,n) for(ll i = (a);i < (n);i++)
#define per(i,a,n) for(ll i = (a);i > (n);i--)
#define lep(i,a,n) for(ll i = (a);i <= (n);i++)
#define pel(i,a,n) for(ll i = (a);i >= (n);i--)
#define clr(a,b) memset((a),(b),sizeof(a))
#define pb push_back
#define mp make_pair
#define all(c) (c).begin(),(c).end()
#define sz size()
#define print(X) cout << (X) << endl
#define fprint(NUM,X) cout << fixed << setprecision(NUM) << (X) << endl
#define fprints(NUM,X,Y) cout << fixed << setprecision(NUM) << (X) << " " << (Y) << endl
const ll INF = 1e+9+7;
ll n,m,l;
string s,t;
ll d[200010],dp[1010][1010];
double w[1000],v[1000];
double box[200010];

ll func(){
  rep(i,0,s.sz)dp[i][0] = 0;
  rep(i,0,t.sz)dp[0][i] = 0;
  rep(i,0,s.sz){
    rep(j,0,t.sz){
      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]);
      }
    }
  }
  return dp[s.sz][t.sz];
}

int main(){
  cin >> n;
  rep(i,0,n){
    cin >> s >> t;
    print(func());
  }
  return 0;
}