Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

// I/O
type Scanner struct {
	sc *bufio.Scanner
}

func NewScanner() *Scanner {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	sc.Buffer(make([]byte, 1024), int(1e+9))
	return &Scanner{sc}
}

func (s *Scanner) nextStr() string {
	s.sc.Scan()
	return s.sc.Text()
}

func (s *Scanner) nextInt() int {
	i, e := strconv.Atoi(s.nextStr())
	if e != nil {
		panic(e)
	}
	return i
}

func (s *Scanner) nextFloat() float64 {
	f, e := strconv.ParseFloat(s.nextStr(), 64)
	if e != nil {
		panic(e)
	}
	return f
}

func (s *Scanner) nextRuneSlice() []rune {
	return []rune(s.nextStr())
}

func (s *Scanner) nextIntSlice(n int) []int {
	res := make([]int, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextInt()
	}
	return res
}

func (s *Scanner) nextFloatSlice(n int) []float64 {
	res := make([]float64, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextFloat()
	}
	return res
}

// Arithmetic
func max(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m < i {
			m = i
		}
	}
	return m
}

func min(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m > i {
			m = i
		}
	}
	return m
}

func abs(x int) int {
	if x > 0 {
		return x
	}
	return -x
}

func pow(x, y int) int {
	res := 1
	for i := 0; i < y; i++ {
		res *= x
	}
	return res
}

func ceil(a, b int) int {
	if a%b == 0 {
		return a / b
	} else {
		return a/b + 1
	}
}

// Sort
type RuneSlice []rune

func (a RuneSlice) Len() int           { return len(a) }
func (a RuneSlice) Less(i, j int) bool { return a[i] < a[j] }
func (a RuneSlice) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }

// Main
func main() {
	sc := NewScanner()
	wtr := bufio.NewWriter(os.Stdout)
	Q := sc.nextInt()
	for q := 0; q < Q; q++ {
		X, Y := sc.nextStr(), sc.nextStr()
		xLen, yLen := len(X), len(Y)
		dp := make([][]int, xLen+1)
		for i := 0; i <= xLen; i++ {
			dp[i] = make([]int, yLen+1)
		}
		for x := 0; x <= xLen; x++ {
			for y := 0; y <= yLen; y++ {
				if x == 0 || y == 0 {
					dp[x][y] = 0
				} else if X[x-1] == Y[y-1] {
					dp[x][y] = dp[x-1][y-1] + 1
				} else {
					dp[x][y] = max(dp[x-1][y], dp[x][y-1])
				}
			}
		}
		fmt.Fprintln(wtr, dp[xLen][yLen])
	}

	wtr.Flush()
}

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

int lcs(string s, string t);
int main(){
  int n; cin >> n;
  string s, t;
  int ans[n];
  for(int i=0; i<n; i++){
    cin >> s >> t;
    ans[i]=lcs(s,t);
  }

  for(int i=0; i<n; i++) cout << ans[i] << endl;

  return 0;
}

int lcs(string s, string t){
  int ans=0;
  int sl=s.length(), tl=t.length();
  int dp[sl+1][tl+1];

  for(int i=0; i<=sl; i++) dp[i][0]=0;
  for(int j=0; j<=tl; j++) dp[0][j]=0;

  s=" "+s;
  t=" "+t;
  for(int i=1; i<=sl; i++){
    for(int j=1; j<=tl; j++){
      if(i==0 || j==0) dp[i][j]=0;
      else if(s[i]==t[j]) dp[i][j]=dp[i-1][j-1]+1;
      else dp[i][j]=max(dp[i][j-1], dp[i-1][j]);
    }

  }

  return dp[sl][tl];
}

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

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

  for (unsigned int i = 1; i <= n; i++)
    dp[0][i] = 0;
  for (unsigned int i = 1; i <= m; i++) {
    for (unsigned int j = 1; j <= n; 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<bits/stdc++.h>
using namespace std;
static const int N = 1000;

int  lcs(string X, string Y)
{
    int c[N + 1][N + 1];
    int m = X.size();
    int n = Y.size();
    int maxl = 0;
    X.insert(0, " ");  // X[0]に空白を挿入
    Y.insert(0, " ");;  // Y[0]に空白を挿入

    for (int i = 1; i <= m; i++) c[i][0] = 0;
    for (int j = 1; j <= n; j++) c[0][j] = 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]);
            // if (c[i][j] > maxl) {
            //     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;
    }
    return 0;
}

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

static const int N=1000;

int Lcs(string X, string Y){
  int c[N+1][N+1], m=X.size(), n=Y.size(), LMAX=0;

  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;

  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]);
      }
      LMAX=max(LMAX, c[i][j]);
    }
  }

  return LMAX;
}

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

  return 0;
}

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

int main(){
	
	vector<int> v;
	int n=0;
	scanf("%d", &n);
	string a;
	string b;
	for (int i = 0; i < n; ++i)
	{
		char a1[1000],b1[1000];
		string a(a1);
		string b(b1);
		vector<vector<int> > dp(int(a.size()), vector<int>(int(b.size())));
		
		if(a[0]==b[0]) dp[0][0]=1;
		for (int i = 0; i < a.size(); ++i)
		{
			if(a[i]==b[0]){
				dp[i][0]=1;
			} else {
				dp[i][0]=dp[i-1][0];
			}
		}
		for (int i = 0; i < b.size(); ++i)
		{
			if(a[0]==b[i]){
				dp[0][i]=1;
			} else {
				dp[0][i]=dp[0][i-1];
			}
		}
		for (int i = 1; i < a.size(); ++i)
		{
			for (int j = 1; j < b.size(); ++j)
			{
				if(a[i]==b[j]){
					dp[i][j]=dp[i-1][j-1]+1;
				} else {
					dp[i][j]=max(dp[i-1][j-1],max(dp[i-1][j],dp[i][j-1]));
				}
			}
		}
		int na=int(a.size());
		int nb=int(b.size());
		v.push_back(dp[na][nb]);
	}
	for (int i = 0; i < v.size(); ++i)
	{
		printf("%d\n",v[i]);
	}

	return(0);
}

C++: #include <iostream>
#include <cstring>
using namespace std;
int main(void)
{
    int n;
    cin>>n;
    for(int i=0;i<n;i++)
    {
        string str1,str2;
        cin>>str1>>str2;
        int lenth1,lenth2;
        lenth1=(int)str1.length();
        lenth2=(int)str2.length();
        int dp[lenth1+1][lenth2+1];
        for(int j=0;j<=lenth1;j++)dp[j][0]=0;
        for(int j=0;j<=lenth2;j++)dp[0][j]=0;
        for(int j=1;j<=lenth1;j++)
        {
            for(int k=1;k<=lenth2;k++)
            {
                if(str1[j-1]==str2[k-1])
                {
                    dp[j][k]=dp[j-1][k-1]+1;
                }
                else dp[j][k]=max(dp[j-1][k],dp[j][k-1]);
            }
        }
        cout<<dp[lenth1][lenth2]<<endl;
    }
    return 0;
}

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

int lcs(string X,string Y){
  int c[N + 1][N + 1];
  int m=X.size();
  int n=Y.size();
  int maxl=0;
  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;

  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;
  }
  return 0;
}