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 <bits/stdc++.h>
using namespace std;
using Int = unsigned long long;
typedef pair<int,int> P;
typedef priority_queue<int> Pr;
Int const MOD = 1000000007;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }


int main(){
    cin.tie(0); ios::sync_with_stdio(false);

    int q; cin>>q;
    for (int i = 0; i < q; i++){
        int dp[1001][1001]={};
        string s1,s2; cin>>s1>>s2;
        for (int j = 0; j < s1.size(); j++){
            for (int k = 0; k < s2.size(); k++){
                if(s1[j]==s2[k]){
                    chmax(dp[j+1][k+1],max(dp[j][k+1],max(dp[j+1][k],dp[j][k]+1)));
                }else chmax(dp[j+1][k+1],max(dp[j][k+1],dp[j+1][k]));
            }
        }
        cout<<dp[s1.size()][s2.size()]<<'\n';
    }
}

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

vector<vector<int> > D(2000, vector<int>(2000, -1));

// Xのi番目以前とYのj番目以前の最長共通部分列の大きさを返す
int lcs(string &X, string &Y, int i, int j)
{
  // メモされているとき
  if (D.at(i).at(j) > -1)
  {
    return D.at(i).at(j);
  }

  // ベースケース
  if (i == 0)
  {
    for (int tmp = 0; tmp <= j; tmp++)
    {
      if (X.at(i) == Y.at(tmp))
      {
        D.at(i).at(j) = 1;
        return 1;
      }
    }
    D.at(i).at(j) = 0;
    return 0;
  }
  if (j == 0)
  {
    for (int tmp = 0; tmp <= i; tmp++)
    {
      if (X.at(tmp) == Y.at(j))
      {
        D.at(i).at(j) = 1;
        return 1;
      }
    }
    D.at(i).at(j) = 0;
    return 0;
  }
  // 再帰ステップ
  int M = 0;
  if (i > 0)
  {
    M = max(M, lcs(X, Y, i - 1, j));
  }
  if (j > 0)
  {
    M = max(M, lcs(X, Y, i, j - 1));
  }
  if ((i > 0 && j > 0) && (X.at(i)) == Y.at(j))
  {
    M = max(M, lcs(X, Y, i - 1, j - 1) + 1);
  }
  D.at(i).at(j) = M;
  return M;
}

int main()
{
  int n;
  cin >> n;
  for (int i = 0; i < n; i++)
  {
    string X, Y;
    cin >> X;
    cin >> Y;
    cout << lcs(X, Y, X.size() - 1, Y.size() - 1) << endl;
    vector<vector<int> > E(2000, vector<int>(2000, -1));
    D = E;
  }
}

C++: #include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>

using namespace std;

int q;
char X[1000], Y[1000];
int dp[1001][1001];

int main(void) {

    scanf("%d", &q);

    for (int i = 0; i < q; ++i) {
        scanf("%s %s", X, Y);
        int xlen = strlen(X), ylen = strlen(Y);
        for (int x = 0; x < xlen; ++x) {
            for (int y = 0; y < ylen; ++y) {
                if (X[x] == Y[y]) {
                    dp[x + 1][y + 1] = dp[x][y] + 1;
                }
                else {
                    if (dp[x + 1][y] > dp[x][y + 1]) {
                        dp[x + 1][y + 1] = dp[x + 1][y];
                    }
                    else {
                        dp[x + 1][y + 1] = dp[x][y + 1];
                    }
                }
            }
        }
        printf("%d\n", dp[xlen][ylen]);
    }

    return 0;
}

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

void solve(){
	string a,b;
	cin >> a >> b;
	int dp[1001][1001];
	memset(dp,0,sizeof(dp));
	for(int i=0;i<=a.size();i++){
		for(int j=0;j<=b.size();j++){
			if(i > 0)
				dp[i][j] = max(dp[i][j],dp[i-1][j]);
			if(j > 0)
				dp[i][j] = max(dp[i][j],dp[i][j-1]);
			if(i > 0 && j > 0)
				dp[i][j] = max(dp[i][j],dp[i-1][j-1] + (a[i-1] == b[j-1] ? 1 : 0));
		}
	}
	cout << dp[a.size()][b.size()] << endl;
}
int main(void) {
	int q;
	cin >> q;
	for(int i=0;i<q;i++){
		solve();
	}
	return 0;
}

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

int LCS(const string &a, const string &b) {
	vector<vector<int>> dp(a.size() + 1, vector<int>(b.size() + 1, 0));
	for (int i = 0; i <= a.size(); i++) {
		for (int j = 0; j <= b.size(); j++) {
			if (i > 0 && j > 0) {
				if (a[i - 1] == b[j - 1]) {
					dp[i][j] = max(dp[i][j], dp[i - 1][j - 1] + 1);
				}
				else {
					dp[i][j] = max(dp[i][j], dp[i - 1][j - 1]);
				}
				dp[i][j] = max(dp[i][j], dp[i][j - 1]);
				dp[i][j] = max(dp[i][j], dp[i - 1][j]);
			}
			else if (i > 0) {
				dp[i][j] = max(dp[i][j], dp[i - 1][j]);
			}
			else if (j > 0) {
				dp[i][j] = max(dp[i][j], dp[i][j - 1]);
			}
		}
	}
	return dp[a.size()][b.size()];
}

int main()
{
	int n;
	string X, Y;
	cin >> n;
	while (n--) {
		cin >> X >> Y;
		cout << LCS(X, Y) << endl;
	}
	return 0;
}

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

#define MAX 1000

int lcs(string X, string Y) {
    int c[MAX+1][MAX+1];
    int m = X.size();
    int n = Y.size();
    int i, j;
    int maxlen = 0;
    X = " " + X;
    Y = " " + Y;

    for (i = 1 ; i <= m ; i++ ) c[i][0] = 0;
    for (j = 1 ; j <= n ; j++ ) c[0][j] = 0;

    for(i = 1 ; i <= m ; i++ ) {
        for(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][j-1], c[i-1][j]);
            }
            maxlen = max(maxlen, c[i][j]);
        }
    }
    return maxlen;
}

int main (void) {
    int N, i;
    string x, y;

    cin >> N;

    for(i = 0 ; i < N ; i++) {
        cin >> x;
        cin >> y;
        cout << lcs(x, y) << endl;
    }
    return 0;
}