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 <algorithm>
#include <string>
using namespace std;
int dp[1005][1005] = { 0 };
int main() {
	int n;
	cin >> n;
	for (int i = 0; i < n; i++) {
		string x, y;
		cin >> x >> y;
		for (int j = 0; j < 1005; j++)
			for (int k = 0; k < 1005; k++) dp[j][k] = 0;
		for (int j = 1; j <= x.size(); j++) {
			for (int k = 1; k <= y.size(); k++) {
				dp[j][k] = max(dp[j][k - 1], dp[j - 1][k]);
				if (x[j - 1] == y[k - 1]) {
					dp[j][k] = max(dp[j][k], dp[j - 1][k - 1] + 1);
				}
			}
		}
		cout << dp[x.size()][y.size()] << endl;
	}
	return 0;
}

C++: #define _GLIBCXX_DEBUG
typedef long long ll;
#include <bits/stdc++.h>

using namespace std;

ll mod = 1000000007;

template<class Type> inline bool chmax(Type& a, Type b) { if (a < b) { a = b; return 1; } return 0; }
template<class Type> inline bool chmin(Type& a, Type b) { if (a > b) { a = b; return 1; } return 0; }

template<class Type>
Type modpow(Type a, Type n, Type mod)
{
	Type res = 1;
	while (0 < n)
	{
		if (n & 1)
		{
			res = res * a % mod;
		}
		a = a * a % mod;
		n >>= 1;
	}
	return res;
}

template<class Type>
Type gcd(Type x, Type y)
{
	Type r;
	if (x < y)
	{
		swap(x, y);
	}

	while (0 < y)
	{
		r = x % y;
		x = y;
		y = r;
	}
	return x;
}

template<class Type>
bool isPrime(Type x)
{
	if (x == 2) return true;
	if (x < 2 || x % 2 == 0) return false;

	for (Type i = 3; i <= sqrt(x); i += 2)
	{
		if (x % i == 0) return false;
	}
	return true;
}

template<class Type>
vector<bool> eratos(Type n)
{
	vector<bool> isPrime(n + 1, true);
	isPrime[0] = isPrime[1] = false;
	for (Type i = 2; i <= n; i++)
	{
		if (isPrime[i])
		{
			Type j = i + i;
			while (j <= n)
			{
				isPrime[j] = false;
				j = j + i;
			}
		}
	}
	return isPrime;
}

bool binarySearchJudge(vector<int> a, int index, int key)
{
	if (key <= a[index]) return true;
	else return false;
}

int binarySearch(vector<int> a, int key)
{
	int ng = -1;
	int ok = a.size();
	while (1 < abs(ng - ok))
	{
		int mid = (ng + ok) / 2;
		if (binarySearchJudge(a, mid, key)) ok = mid;
		else ng = mid;
	}
	return a[ok] == key;
}

int lcs(string x, string y)
{
	int m = x.size();
	int n = y.size();
	vector<vector<int>> dp(m, vector<int>(n));

	dp[0][0] = (x[0] == y[0]) ? 1 : 0;
	for (int i = 1; i < m; i++)
	{
		if (y[0] == x[i]) dp[i][0] = 1;
		else dp[i][0] = max(dp[i - 1][0], 0);
	}
	for (int i = 1; i < n; i++)
	{
		if (x[0] == y[i]) dp[0][i] = 1;
		else dp[0][i] = max(dp[0][i - 1], 0);
	}

	for (int i = 1; i < m; i++)
	{
		for (int j = 1; j < n; j++)
		{
			if (x[i] == y[j]) dp[i][j] = dp[i - 1][j - 1] + 1;
			else dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]);
		}
	}
	return dp[m - 1][n - 1];
}

int main()
{
	int n;
	cin >> n;
	for (int i = 0; i < n; i++)
	{
		string x, y;
		cin >> x >> y;
		cout << lcs(x, y) << endl;
	}
}

C++: #include <iostream>
#include <string>
#include <map>
#include <set>
#include <algorithm>
using namespace std;
#define MAX 100000

static const int N =100;

int lcs(string X,string Y){
  int c[N+1][N+1];
  int m=X.size();
  int n=Y.size();
  int ans=0;
  X= ' '+X;
  Y= ' '+Y;
  for(int i;i<=m;i++)c[i][0]=0;
  for(int j;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]);
      }
      ans=max(ans,c[i][j]);
    }
  
  }
  return ans;
}

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

C++: #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 maxl = 0;
  x = ' ' + x;
  y = ' ' + y;
  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 q;
  cin >> q;

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

  return 0;
}

C++: #include<iostream>
#include<string>
using namespace std;
const int N_MAX = 1005;
short res[N_MAX][N_MAX];

int lcs(string X, string Y){
	int xLen = X.size();
	int yLen = Y.size();
	int maxRes=0;
	X=' '+X;
	Y=' '+Y;
	for(int i=1;i<=xLen;i++){
		for(int j=1;j<=yLen;j++){
			if(X[i]==Y[j]){
				res[i][j] = res[i-1][j-1]+1;
			}else if(res[i][j-1]>=res[i-1][j]){
				res[i][j] = res[i][j-1];
			}else{
				res[i][j] = res[i-1][j];
			}
			maxRes = (res[i][j]>maxRes)?res[i][j]:maxRes;
		}
	}
	return maxRes;
}

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