Go: package main

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

var (
	nstr   func() string
	stdout *bufio.Writer
)

func init() {
	nstr = newReadString(os.Stdin)
	stdout = bufio.NewWriter(os.Stdout)
}

func main() {
	defer stdout.Flush()

	n := nint()
	xList := make([]string, n)
	yList := make([]string, n)

	for i:=0;i<n ;i++  {
		xList[i] = nstr()
		yList[i] = nstr()
	}

	for i := 0; i<n	; i++  {
		fmt.Println(lcs(xList[i], yList[i]))
	}

}

func lcs(x string, y string) int{
	var m = len(x)
	var n = len(y)

	c := make([][]int, m+1)
	for i:= range c{
		c[i] = make([]int, n+1)
	}
	for i:=	1;i<=m ;i++  {
		for j:=1;j<=n ;j++  {
			if x[i-1] == y[j-1]{
				c[i][j] = c[i-1][j-1] + 1
			}else{
				c[i][j] = int(math.Max(float64(c[i-1][j]), float64(c[i][j-1])))
			}


		}
	}
	return c[m][n]

}


func newReadString(ior io.Reader) func() string {
	r := bufio.NewScanner(ior)
	r.Buffer(make([]byte, 1024), int(1e+11))
	r.Split(bufio.ScanWords)

	return func() string {
		if !r.Scan() {
			panic("Scan failed")
		}
		return r.Text()
	}
}

func nint64() int64 {
	i, err := strconv.ParseInt(nstr(), 0, 64)
	if err != nil {
		panic(err.Error())
	}
	return i
}

func nint() int {
	return int(nint64())
}

func getIntSlice(n int) []int {
	b := make([]int, n)
	for i := 0; i < n; i++ {
		b[i] = nint()
	}
	return b
}

func getStringSlice(n int) []string {
	b := make([]string, n)
	for i := 0; i < n; i++ {
		b[i] = nstr()
	}
	return b
}

func gcd(x, y int) int {
	if y == 0 {
		return x
	}
	return gcd(y, x%y)
}

func lcm(x, y int) int {
	return x * y / gcd(x, y)
}

func contains(s []int, e int) bool {
	for _, a := range s {
		if a == e {
			return true
		}
	}
	return false
}

func bin(i int, prefix bool) string {
	i64 := int64(i)

	if prefix {
		return "0b" + strconv.FormatInt(i64, 2)
	} else {
		return strconv.FormatInt(i64, 2)
	}
}

func strReverse(s string) string {
	runes := []rune(s)
	for i, j := 0, len(runes)-1; i < j; i, j = i+1, j-1 {
		runes[i], runes[j] = runes[j], runes[i]
	}

	return string(runes)
}

C++: #include <bits/stdc++.h>
using namespace std;
using Int = unsigned long long;
typedef pair<int,int> P;
typedef priority_queue<int> Pr;
Int const MOD = 1000000007;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }


int main(){
    cin.tie(0); ios::sync_with_stdio(false);

    int q; cin>>q;
    for (int i = 0; i < q; i++){
        int dp[1001][1001]={};
        string s1,s2; cin>>s1>>s2;
        for (int j = 0; j < s1.size(); j++){
            for (int k = 0; k < s2.size(); k++){
                if(s1[j]==s2[k]){
                    chmax(dp[j+1][k+1],max(dp[j][k+1],max(dp[j+1][k],dp[j][k]+1)));
                }else chmax(dp[j+1][k+1],max(dp[j][k+1],dp[j+1][k]));
            }
        }
        cout<<dp[s1.size()][s2.size()]<<'\n';
    }
}

C++: #include <bits/stdc++.h>
using namespace std;

vector<vector<int> > D(2000, vector<int>(2000, -1));

// Xのi番目以前とYのj番目以前の最長共通部分列の大きさを返す
int lcs(string &X, string &Y, int i, int j)
{
  // メモされているとき
  if (D.at(i).at(j) > -1)
  {
    return D.at(i).at(j);
  }

  // ベースケース
  if (i == 0)
  {
    for (int tmp = 0; tmp <= j; tmp++)
    {
      if (X.at(i) == Y.at(tmp))
      {
        D.at(i).at(j) = 1;
        return 1;
      }
    }
    D.at(i).at(j) = 0;
    return 0;
  }
  if (j == 0)
  {
    for (int tmp = 0; tmp <= i; tmp++)
    {
      if (X.at(tmp) == Y.at(j))
      {
        D.at(i).at(j) = 1;
        return 1;
      }
    }
    D.at(i).at(j) = 0;
    return 0;
  }
  // 再帰ステップ
  int M = 0;
  if (i > 0)
  {
    M = max(M, lcs(X, Y, i - 1, j));
  }
  if (j > 0)
  {
    M = max(M, lcs(X, Y, i, j - 1));
  }
  if ((i > 0 && j > 0) && (X.at(i)) == Y.at(j))
  {
    M = max(M, lcs(X, Y, i - 1, j - 1) + 1);
  }
  D.at(i).at(j) = M;
  return M;
}

int main()
{
  int n;
  cin >> n;
  for (int i = 0; i < n; i++)
  {
    string X, Y;
    cin >> X;
    cin >> Y;
    cout << lcs(X, Y, X.size() - 1, Y.size() - 1) << endl;
    vector<vector<int> > E(2000, vector<int>(2000, -1));
    D = E;
  }
}

C++: #include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>

using namespace std;

int q;
char X[1000], Y[1000];
int dp[1001][1001];

int main(void) {

    scanf("%d", &q);

    for (int i = 0; i < q; ++i) {
        scanf("%s %s", X, Y);
        int xlen = strlen(X), ylen = strlen(Y);
        for (int x = 0; x < xlen; ++x) {
            for (int y = 0; y < ylen; ++y) {
                if (X[x] == Y[y]) {
                    dp[x + 1][y + 1] = dp[x][y] + 1;
                }
                else {
                    if (dp[x + 1][y] > dp[x][y + 1]) {
                        dp[x + 1][y + 1] = dp[x + 1][y];
                    }
                    else {
                        dp[x + 1][y + 1] = dp[x][y + 1];
                    }
                }
            }
        }
        printf("%d\n", dp[xlen][ylen]);
    }

    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;

void solve(){
	string a,b;
	cin >> a >> b;
	int dp[1001][1001];
	memset(dp,0,sizeof(dp));
	for(int i=0;i<=a.size();i++){
		for(int j=0;j<=b.size();j++){
			if(i > 0)
				dp[i][j] = max(dp[i][j],dp[i-1][j]);
			if(j > 0)
				dp[i][j] = max(dp[i][j],dp[i][j-1]);
			if(i > 0 && j > 0)
				dp[i][j] = max(dp[i][j],dp[i-1][j-1] + (a[i-1] == b[j-1] ? 1 : 0));
		}
	}
	cout << dp[a.size()][b.size()] << endl;
}
int main(void) {
	int q;
	cin >> q;
	for(int i=0;i<q;i++){
		solve();
	}
	return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;

int LCS(const string &a, const string &b) {
	vector<vector<int>> dp(a.size() + 1, vector<int>(b.size() + 1, 0));
	for (int i = 0; i <= a.size(); i++) {
		for (int j = 0; j <= b.size(); j++) {
			if (i > 0 && j > 0) {
				if (a[i - 1] == b[j - 1]) {
					dp[i][j] = max(dp[i][j], dp[i - 1][j - 1] + 1);
				}
				else {
					dp[i][j] = max(dp[i][j], dp[i - 1][j - 1]);
				}
				dp[i][j] = max(dp[i][j], dp[i][j - 1]);
				dp[i][j] = max(dp[i][j], dp[i - 1][j]);
			}
			else if (i > 0) {
				dp[i][j] = max(dp[i][j], dp[i - 1][j]);
			}
			else if (j > 0) {
				dp[i][j] = max(dp[i][j], dp[i][j - 1]);
			}
		}
	}
	return dp[a.size()][b.size()];
}

int main()
{
	int n;
	string X, Y;
	cin >> n;
	while (n--) {
		cin >> X >> Y;
		cout << LCS(X, Y) << endl;
	}
	return 0;
}

C++: #include <cstdio>
#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 i, j;
    int maxlen = 0;
    X = " " + X;
    Y = " " + Y;

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

    for(i = 1 ; i <= m ; i++ ) {
        for(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][j-1], c[i-1][j]);
            }
            maxlen = max(maxlen, c[i][j]);
        }
    }
    return maxlen;
}

int main (void) {
    int N, i;
    string x, y;

    cin >> N;

    for(i = 0 ; i < N ; i++) {
        cin >> x;
        cin >> y;
        cout << lcs(x, y) << endl;
    }
    return 0;
}