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;
int dp[1010][1010];
int main(){
  int q;
  cin>>q;
  for(int cn=0;cn<q;cn++){
    string x,y;
    cin>>x>>y;
    memset(dp,0,sizeof(dp));
    for(int i=1;i<=x.size();i++){
      for(int j=1;j<=y.size();j++){
	if(x[i-1]==y[j-1])dp[i][j]=dp[i-1][j-1]+1;
	dp[i][j]=max(dp[i-1][j],dp[i][j]);
	dp[i][j]=max(dp[i][j-1],dp[i][j]);
      }
    }
    cout<<dp[x.size()][y.size()]<<endl;
  }
  return 0;
}

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

int lcs(string X, string Y) {
  int dp[1000 + 1][1000 + 1];
  int max = 0;
  X = ' ' + X;
  Y = ' ' + Y;
  for (unsigned int i = 1; i <= X.size() - 1; i++)
    dp[i][0] = 0;

  for (unsigned int i = 1; i <= Y.size() - 1; i++)
    dp[0][i] = 0;
  for (unsigned int i = 1; i <= X.size() - 1; i++) {
    for (unsigned int j = 1; j <= Y.size() - 1; j++) {
      if (X[i] == Y[i])
	dp[i][j] = dp[i - 1][j - 1] + 1;
      else if (dp[i - 1][j] >= dp[i][j - 1])
	dp[i][j] = dp[i - 1][j];
      else
	dp[i][j] = dp[i][j - 1];

      max = (max < dp[i][j]) ? dp[i][j] : max;
    }
  }

  return max;
}

int main(int argc, char const *argv[]) {
  int N;
  cin >> N;

  for (int i = 0; i < N; i++) {
    string X, Y;
    cin >> X >> Y;

    cout << lcs(X, Y) << endl;
  }

  return 0;
}

C++: #include <stdio.h>
#include <stdint.h>
#include <iostream>
#include <fstream>
#include <cassert>
#include <climits>
#include <vector>
#include <memory>
using namespace std;

#define DEBUG (0)

#if DEBUG
#define DPRINTF(...) do { \
    printf("D(L%d) %s: ", __LINE__, __func__); \
    printf(__VA_ARGS__); \
  } while (false)
#else
#define DPRINTF(...)
#endif // DEBUG


class LongestCommonSubsequence {
public:
  LongestCommonSubsequence(string s0, string s1) :
    s0_(s0),
    s1_(s1)
    {
      size_ = s0_.length() * s1_.length();
      pLongest_ = new int [size_];
      for (int i = 0; i < size_; i++)
        pLongest_[i] = kInvalid;
    }

  ~LongestCommonSubsequence()
  {
    if (pLongest_)
      free(pLongest_);
  }

  int getLCSlen();
  void printLength();

  const int kInvalid = -1;

private:
  string s0_;
  string s1_;
  int *pLongest_;
  int size_;

  int getIndex(int x, int y);
  int getLCSlenOf(int n0, int n1);
};

/*********************************
Input:
  x[0], x[1], x[2], ..., x[n-1]
  y[0], y[1], y[2], ..., y[m-1]

Algorithm:
  if x[n-1] == y[m-1]
    LCS(n-1, m-1) = LCS(n-2,m-2) + 1

  if x[n-1] != y[m-1]
    LCS(n-1, m-1) = max(LCS(n-2, m-1), LCS(n-1, m-2))

  LCS(0, *) = LCS(*, 0) = 0;

  a b c b d a b
  b d c a b a
*********************************/

int LongestCommonSubsequence::getLCSlen()
{
  int n0 = s0_.length() - 1;
  int n1 = s1_.length() - 1;
  return getLCSlenOf(n0, n1);
}


int LongestCommonSubsequence::getLCSlenOf(int n0, int n1)
{
  DPRINTF("n0 %d  n1 %d\n", n0, n1);

  assert(-1 <= n0 && n0 < static_cast<int>(s0_.length()));
  assert(-1 <= n1 && n1 < static_cast<int>(s1_.length()));

  if (n0 < 0  || n1 < 0)
    return 0;

  const int idx = getIndex(n0, n1);

  if (pLongest_[idx] != kInvalid)
    return pLongest_[idx];

  if (s0_[n0] == s1_[n1])
    pLongest_[idx] = getLCSlenOf(n0 - 1, n1 - 1) + 1;
  else
    pLongest_[idx] = max(getLCSlenOf(n0 - 1, n1), getLCSlenOf(n0, n1 - 1));

  return pLongest_[idx];
}


int LongestCommonSubsequence::getIndex(int x, int y)
{
  return y * s0_.length() + x;
}


void LongestCommonSubsequence::printLength()
{
  for (int i = 0; i < s0_.length(); i++)
    for (int j = 0; j < s1_.length(); j++)
      DPRINTF("pLongest_[%d][%d] %d\n", i, j, pLongest_[getIndex(i, j)]);
}


int main()
{
  int numOfPair;
  cin >> numOfPair; cin.ignore();

  DPRINTF("num of pair %d\n", numOfPair);

  for (int i = 0; i < numOfPair; i++)
  {
    string str0, str1;
    cin >> str0 >> str1; cin.ignore();

    DPRINTF("str0 %s  str1 %s\n", str0.c_str(), str1.c_str());

    LongestCommonSubsequence lcs(str0, str1);
    cout << lcs.getLCSlen() << endl;

#if (1) && DEBUG
    lcs.printLength();
#endif
  }

  return 0;
}

C++: #include <iostream>
#include <cmath>
#include <vector>
#include <cstring>

constexpr int MAX = 1000;
char ls[MAX];
char rs[MAX];
int table[MAX + 1][MAX + 1];


void calc_lcs() {
    scanf("%s", ls);
    scanf("%s", rs);
    int l_len = int(std::strlen(ls));
    int r_len = int(std::strlen(rs));
    for (int i = 0; i < l_len; i++) {
        table[i][0] = 0;
    }
    for (int i = 0; i < r_len; i++) {
        table[0][i] = 0;
    }

    for (int l_i = 1; l_i < l_len + 1; l_i++) {
        for (int r_i = 1; r_i < r_len + 1; r_i++) {
            if (ls[l_i - 1] == rs[r_i - 1]) {
                table[l_i][r_i] = table[l_i - 1][r_i - 1] + 1;
            } else {
                table[l_i][r_i] = std::max(table[l_i][r_i - 1], table[l_i - 1][r_i]);
            }
        }
    }
    std::cout << table[l_len][r_len] << std::endl;
}

int main() {
    int N;
    scanf("%d", &N);
    for (int i = 0; i < N; i++) {
        calc_lcs();
    }
}