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 <algorithm>
#include <iostream>
#include <string>
#include <cassert>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <deque>
#include <iomanip>
#include <limits>
#include <map>
#include <queue>
#include <stack>
#include <vector>

#define FOR(i,k,n) for(int (i) = (k); (i) < (n); ++(i))
#define rep(i,n) FOR(i,0,n)
#define pb push_back
#define all(v) begin(v), end(v)
#define debug(x) cerr << #x << ": " << x << endl
#define debug2(x,y) cerr << #x << ": " << x << ", " << #y << ": " << y << endl

using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> i_i;
typedef pair<i_i, int> p_i;
typedef vector<int> vi;
typedef vector<vector<int>> vvi;
template<class T> using vv=vector<vector<T>>;
typedef deque<int> di;
typedef deque<deque<int>> ddi;


int main() {
    int q;
    cin >> q;
    rep(i,q) {
        string x,y;
        cin >> x >> y;
        int dp[1050][1050] = {};
        rep(i,(int)x.length()) {
            rep(j,(int)y.length()) {
                if(i == 0 && j == 0) {
                    if(x[i] == y[j]) {
                        dp[i][j] = 1;
                    } 
                } else if(i == 0) {
                    if(x[i] == y[j]) {
                        dp[i][j] = 1;
                    } else { 
                        dp[i][j] = dp[i][j-1];
                    }
                } else if(j == 0) {
                    if(x[i] == y[j]) {
                        dp[i][j] = 1;
                    } else { 
                        dp[i][j] = dp[i-1][j];
                    }
                } else 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]);
                }
            }
        }
        cout << dp[x.length()-1][y.length()-1] << endl;
    }
	return 0;
}

C++: // input: alds1_10_c.in
#include<iostream>
#include<algorithm>
#define MAX_X 1000
#define MAX_Y 1000
using namespace std;

int c[MAX_X+1][MAX_Y+1];

int lcs(string& a, string& b) {
  a = ' ' + a;
  b = ' ' + b;

  for(int i=0; i<a.length(); i++) {
    c[i][0] = 0;
  }
  for(int i=0; i<b.length(); i++) {
    c[0][i] = 0;
  }

  for(int i=1; i<a.length(); i++) {
    for(int j=1; j<b.length(); j++) {
      if(a[i] == b[j]) {
        c[i][j] = c[i-1][j-1] + 1;
      } else {
        c[i][j] = max(c[i][j-1], c[i-1][j]);
      }
    }
  }

  return c[a.length()-1][b.length()-1];
}

int main() {
  int n;
  string a, b;
  cin >> n;
  for(int i=0; i<n; i++) {
    cin >> a >> b;

    cout << lcs(a, b) << endl;
  }
}

C++: #include <iostream>
#include <algorithm>
#include <string>
using namespace std;
const int MAX=1001;
int lcs(string X,string Y) 
{
	int i=0,j=0,c[MAX][MAX],x=X.length(),y=Y.length();
	for(i=0;i<=x;i++)c[i][0]=0;
	for(i=0;i<=y;i++)c[0][i]=0;
	for(i=1;i<=x;i++) 
	for(j=1;j<=y;j++) 
	if(X[i-1]==Y[j-1])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];
	return c[x][y];
}
int main()
{
	int n;cin>>n;
	string X,Y;
	while(n--)
	{
		cin>>X>>Y;
		cout<<lcs(X,Y)<<endl;
	}
}

C++: #include<iostream>
#include<string>
#include<algorithm>
using namespace std;
#define MAX 1000
int dp[MAX + 1][MAX + 1];
int LCS(string STR1, string STR2)
{
	int length1 = STR1.size();
	int length2 = STR2.size();
	STR1 = ' ' + STR1;
	STR2 = ' ' + STR2;
	for (int i = 0; i <= length1; i++)
	{
		for (int l = 0; l <= length2; l++)dp[i][l] = 0;
	}
	for (int i = 1; i <= length1; i++)
	{
		for (int l = 1; l <= length2; l++)
		{
			if (STR1[i] == STR2[l])dp[i][l] =dp[i-1][l-1]+1;
			else
			{
				dp[i][l]=max(dp[i - 1][l], dp[i][l - 1]);
			}
		}
	}
	return dp[length1][length2];
}
int main()
{
	int q;
	cin >> q;
	for (int i = 0; i < q; i++)
	{
		string str1, str2;
		cin >> str1 >> str2;
		cout << LCS(str1, str2) << endl;
	}
	return 0;
}

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

int lcs(string str1, string str2)
{
	int len[1001][1001] = { 0 };

	int len1 = str1.size();
	int len2 = str2.size();
	str1 = ' ' + str1;
	str2 = ' ' + str2;
	for (int i = 0; i <= len1; i++)
	{
		for (int l = 0; l <= len2; l++)len[i][l] = 0;
	}
	for (int i = 1; i <= len1; i++)
	{
		for (int l = 1; l <= len2; l++)
		{
			if (str1[i] == str2[l]) len[i][l] = len[i - 1][l - 1] + 1;
			else
			{
				len[i][l] = max(len[i - 1][l], len[i][l - 1]);
			}
		}
	}
	return len[len1][len2];
}
int main()
{
	int n;
	string str1, str2;

	cin >> n;
	for (int i = 0; i < n; i++)
	{
		cin >> str1 >> str2;
		cout << lcs(str1, str2) << endl;
	}

	return 0;
}