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;
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 = 0; 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;
}

C++: #include <iostream>
#include <vector>
#include <string>
#include <cmath>
#include <set>
#include <algorithm>
#include <array>
#include <complex>
#include <utility>
#include <map>
#include <inttypes.h>
int c[1001][1001] = {0};
int LCS(std::string s, std::string t){
    int n, m;
    n = s.size();
    m = t.size();
    int maxlen = 0;
    for(int i = 1; i <= n; i++){
        c[i][0] = 0;
    }
    for(int i = 1; i <= m; i++){
        c[0][i] = 0;
    }
    for(int i = 1; i <= n; i++){
        for(int j = 1; j <= m; j++){
            if(s[i - 1] == t[j - 1]){
                c[i][j] = c[i - 1][j - 1] + 1;
            }
            else{
                c[i][j] = std::max(c[i - 1][j], c[i][j - 1]);
            }
            maxlen = std::max(maxlen, c[i][j]);
        }
    }
    return maxlen;
}
int main(){
    int N;

    std::cin >> N;
    std::string s1, s2;
    for(int i = 0; i<N; i++){
        std::cin >> s1 >> s2;
       
        std::cout << LCS(s1,s2) << std::endl;
    }
    return 0;
}

C++: #include <iostream>
#include <string>
#include <vector>
#include <set>
#include <cmath>
#include <algorithm>
#include <iomanip>
#include <queue>
using ll = long long;
using namespace std;

int const MOD = 1e9 + 7;
int main(void)
{
    int N;
    cin >> N;
    for (int i = 0; i < N; ++i)
    {
        string s, t;
        cin >> s >> t;

        int dp[1010][1010];
        for (int i = 0; i < 1010; ++i)
            for (int j = 0; j < 1010; ++j)
                dp[i][j] = 0;

        int n = s.size();
        int m = t.size();

        for (int i = 0; i < n; ++i)
        {
            for (int j = 0; j < m; ++j)
            {
                if (s[i] == t[j])
                {
                    dp[i + 1][j + 1] = max(dp[i + 1][j + 1], dp[i][j] + 1);
                }
                else
                {
                    dp[i + 1][j] = max(dp[i + 1][j], dp[i][j]);
                    dp[i][j + 1] = max(dp[i][j + 1], dp[i][j]);
                    dp[i + 1][j + 1] = max({dp[i + 1][j + 1], dp[i + 1][j], dp[i][j + 1]});
                }
            }
        }

        cout << dp[n][m] << endl;
    }
    return 0;
}

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

int dp[1000+1][1000+1];

int main() {
    int n; 
    cin >> n;
    while(n--) {
        string s, t; cin >> s >> t;
        int N = s.length();
        int M = t.length();
        dp[0][0] = 0;
        for(int i = 0; i < N; i++) {
            for(int j = 0; j < M; j++) {
                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]);
            }
        }
        cout << dp[N][M] << endl;
    }
    return 0;
}

C++: #include <iostream>
#include <cstring>
#include <algorithm>
#include <climits>
#include <string>
#include <vector>

using namespace std;
int q;
string text;
int ans[160];
int dp[1100][1100];

int main(){
    cin >> q;
    vector<string> texts;

    for(int i=0;i<q*2;i++){
         cin >> text;
         texts.push_back(text);
    }
    for(int k=0;k<q;k++){
        memset(dp, 0, sizeof(dp));
        for(int i=0;i<texts[2*k].size();i++){
            for(int j=0;j<texts[2*k+1].size();j++){
                if(texts[2*k][i]==texts[2*k+1][j]) dp[i+1][j+1] = max(dp[i][j]+1, max(dp[i+1][j], dp[i][j+1]));
                else dp[i+1][j+1] = max(dp[i+1][j], dp[i][j+1]);
            }
        }
        ans[k]=dp[texts[2*k].size()][texts[2*k+1].size()];
    } 
    for(int i=0;i<q;i++)cout << ans[i] << endl;
}

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

int lcs(string, string);

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;
}

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 = 0; 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;
}