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 <cstdio>
#include <cstring>
#include <algorithm>

#define SIZE 1001
class TLcsSolver
{
    int FTable[SIZE][SIZE];
    const char* FArray1;
    const char* FArray2;
    const int Fn1;
    const int Fn2;

    int Count(int i, int j)
    {
        if(i == 0 || j == 0) return 0;
        if(FArray1[i-1] == FArray2[j-1]){
            return FTable[i-1][j-1] + 1;
        }
        return std::max(FTable[i-1][j], FTable[i][j-1]);
    }
    void Solve()
    {
        for(std::size_t i = 1; i < Fn1; ++i){
            for(std::size_t j = 1; j < Fn2; ++j){
                FTable[i][j] = Count(i, j);
            }
        }
    }
    void Print()const
    {
        for(std::size_t i = 0; i < Fn1; ++i){
            for(std::size_t j = 0; j < Fn2; ++j){
                printf("%d\t", FTable[i][j]);
            }
            printf("\n");
        }
    } 
public:
    TLcsSolver(const char* a, const char* b)
     : FArray1(a), FArray2(b)
     , Fn1(std::strlen(a)), Fn2(std::strlen(b))
    {
        Solve();
        // Print();
    }
    int Answer()const
    {
        return FTable[Fn1-1][Fn2-1];
    }
};

int main()
{
    int n;
    std::scanf("%d\n", &n);
    char a[SIZE];
    char b[SIZE];
    for(int i = 0; i < n; ++i){
        std::fgets(a, SIZE, stdin);
        std::fgets(b, SIZE, stdin);
        std::printf("%d\n", TLcsSolver(a, b).Answer());
    }
    return 0;
}

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

int dp[1002][1002];

int lcs(string s1,string s2) {
    int m = s1.length();
    int n = s2.length();
    s1 = " " + s1;
    s2 = " " + s2;
    for(int i=1;i<=m;i++) dp[i][0] = 0;
    for(int i=1;i<=n;i++) dp[0][i] = 0;
    int rec = 0;
    for(int i=1;i<=m;i++) {
        for(int j=1;j<=n;j++) {
            if(s1[i] == s2[j]) {
                dp[i][j] = dp[i-1][j-1] + 1;
            } else {
                dp[i][j] = max(dp[i-1][j],dp[i][j-1]);
            }
            rec = max(rec,dp[i][j]);
        }
    }
    return rec;
}

int main() {
    int n; cin >> n;
    while(n--) {
        string s1,s2; cin >> s1 >> s2;
        cout << lcs(s1,s2) << endl;
    }
    return 0;
}

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

static const int max_n = 1000;
string s1, s2;
int q, c[max_n + 1][max_n + 1];

int lcs(string X, string Y){
	int m = X.size();
	int n = Y.size();
	int maxl = 0;
	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 if(c[i - 1][j] >= c[i][j - 1]){
				c[i][j] = c[i - 1][j];
			}
			else{
				c[i][j] = c[i][j - 1];
			}
			maxl = max(maxl, c[i][j]);
		}
	}
	return maxl;
}

int main(void){
	cin >> q;
	for( int i = 1; i <= q; i++ ){
		cin >> s1 >> s2;
		cout << lcs(s1, s2) << endl;
	}
	return 0;
}

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

#define MAX_N 1000
#define MAX_M 1000

//入力
int n;
string s, t;
//char s[MAX_N], t[MAX_M];

int dp[MAX_N + 1][MAX_M + 1]; //DPテーブル

void solve(){
	for(int i = 0; i < s.size(); i++){
		for(int j = 0; j < t.size(); j++){
			if(s[i] == t[j]){
				dp[i + 1][j + 1];
					dp[i + 1][j + 1] = dp[i][j] + 1;
				} else {
					dp[i + 1][j + 1] = max(dp[i][j], dp[i + 1][j]);
				}
			}
		}
		printf("%d\n", dp[s.size()][t.size()]);
}

int main(){
	cin >> n;
	for(int i = 0; i < n; i++){
		cin >> s >> t;
		solve();
	}
}

C++: #include <iostream>
#include <string>
#include <algorithm>

using namespace std;

static const int N = 1000;

int lcs(string str1, string str2)
{
	int c[N + 1][N + 1];
	int m = str1.size();
	int n = str2.size();
	int maxl = 0;
	str1 = ' ' + str1;
	str2 = ' ' + str2;

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

	for (int i = 1; i <= m; i++)
	{
		for (int j = 1; j <= n; j++)
		{
			if (str1[i] == str2[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 str1, str2;
	int n;
	cin >> n;
	for (int i = 0; i < n; i++)
	{
		cin >> str1 >> str2;
		cout << lcs(str1, str2) << endl;
	}
	return 0;
}

C++: #include <algorithm>
#include <cstdio>
#include <iostream>
#include <string>

using namespace std;

int LCS(string X, string Y) {

	int m, n;
	m = X.size();
	n = Y.size();

	int c[m + 1][n + 1];

	for (int i = 0; i <= m; ++i) {
		c[i][0] = 0;
	}
	for (int i = 0; i <= n; ++i) {
		c[0][i] = 0;
	}

	X = ' ' + X;
	Y = ' ' + Y;

	int maxl = 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() {

	int q;
	scanf("%d", &q);

	for (int i = 0; i < q; ++i) {
		string X, Y;
		cin >> X >> Y;
		cout << LCS(X, Y) << endl;
	}

	return 0;

}