Go: package main

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

type Position struct {
	X int
	Y int
}

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	n, err := nextInt(sc)
	if err != nil {
		panic(err)
	}
	for i := 0; i < n; i++ {
		strX := nextText(sc)
		strY := nextText(sc)
		fmt.Println(calcLcs(strX, strY))
	}
}

func calcLcs(strX, strY string) int {
	return lcs(strX, strY, Position{0, 0}, make(map[Position]int))
}

func lcs(strX string, strY string, position Position, memo map[Position]int) int {
	if position.X >= len(strX) || position.Y >= len(strY) {
		return 0
	}
	if v, ok := memo[position]; ok {
		return v
	}
	if strX[position.X] == strY[position.Y] {
		result := lcs(strX, strY, Position{position.X + 1, position.Y + 1}, memo)
		memo[position] = result + 1
		return memo[position]
	} else {
		result1 := lcs(strX, strY, Position{position.X + 1, position.Y}, memo)
		result2 := lcs(strX, strY, Position{position.X, position.Y + 1}, memo)
		var result int
		if result1 > result2 {
			result = result1
		} else {
			result = result2
		}
		memo[position] = result
		return result
	}
}

func nextInt(sc *bufio.Scanner) (int, error) {
	sc.Scan()
	return strconv.Atoi(sc.Text())
}

func nextText(sc *bufio.Scanner) string {
	sc.Scan()
	return sc.Text()
}

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

const int IMINUS_JMINUS = 1, IMINUS = 2, JMINUS = 3;

struct state
{
    int length, from;
};

void lcs(string &s, string &t)
{
    state dp[s.length() + 1][t.length() + 1];
    memset(dp, 0, sizeof(dp));
    
    //cout << dp[0][0].length << endl;
    for (int i = 1; i < s.length() + 1; i++) {
        for (int j = 1; j < t.length() + 1; j++) {
            //if (i == 5 && j == 2) {
            //    cout << "" << endl;
            //}
            if (s[i - 1] == t[j - 1]){
                if (dp[i][j].length < dp[i - 1][j - 1].length + 1)
                {
                    dp[i][j].length = dp[i - 1][j - 1].length + 1;
                    dp[i][j].from = IMINUS_JMINUS;
                }
            } else {
                if (dp[i][j].length < dp[i - 1][j].length)
                    dp[i][j].length = dp[i - 1][j].length, dp[i][j].from = IMINUS;
                if (dp[i][j].length < dp[i][j - 1].length)
                    dp[i][j].length = dp[i][j - 1].length, dp[i][j].from = JMINUS;
            }
            //cout << "i,j" << i << ", " << j << ":" <<  dp[i][j].length << endl;
        }
    }
    cout << dp[s.length()][t.length()].length << endl;
}

int main(int argc, char *argv[])
{
    
 
    cin.tie(0);
    ios::sync_with_stdio(false);
    int n;
    cin >> n;
    string s, t;
    while (n--) {
        cin >> s >> t;
        lcs(s, t);
    }
    
    
    
    return 0;
}

C++: #include<iostream>
#include<sstream>
#include<fstream>
#include<string>
#include<vector>
#include<deque>
#include<queue>
#include<stack>
#include<set>
#include<map>
#include<algorithm>
#include<functional>
#include<utility>
#include<bitset>
#include<cmath>
#include<cstdlib>
#include<ctime>
#include<cstdio>

using namespace std;

#define REP(i,n) for(int i=0;i<int(n);i++)
#define foreach(c,itr) for(__typeof((c).begin()) itr=(c).begin();itr!=(c).end();itr++)
typedef long long ll;
typedef pair<int,int> P;

int dp[1010][1010];

int main(void){
	int i,j,k;

	cin.tie(0);
	ios_base::sync_with_stdio(false);

	int q;
	cin >> q;
	for(i=0;i<q;i++){
		string x,y;
		cin >> x >> y;
		int n=x.size(),m=y.size();

		for(j=0;j<=n;j++) for(k=0;k<=m;k++) dp[j][k]=0;

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

		cout << dp[n][m] << endl;

	}

	return 0;
}

C++: #include<bits/stdc++.h>
#define rep(i,n)for(int i=0;i<n;i++)
using namespace std;

int dp[1001][1001];
int main() {
	int q; scanf("%d", &q);
	rep(i, q) {
		string x, y; cin >> x >> y;
		rep(i, x.size())rep(j, y.size()) {
			if (x[i] == y[j])dp[i + 1][j + 1] = dp[i][j] + 1;
			else dp[i + 1][j + 1] = max(dp[i][j + 1], dp[i + 1][j]);
		}
		printf("%d\n", dp[x.size()][y.size()]);
	}
}

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

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

	int len1 = str1.length();
	int len2 = str2.length();
	//str1 = ' ' + str1;
	//str2 = ' ' + str2;

	for (int i = 0; i <= len1; i++)
		for (int j = 0; j <= len2; j++) len[i][j] = 0;

	for (int i = 1; i <= len1; i++)
	{
		for (int j = 1; j <= len2; j++)
		{
			if (str1[i] == str2[j]) len[i][j] = len[i - 1][j - 1] + 1;
			else len[i][j] = max(len[i - 1][j], len[i][j - 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;
}

C++: #include <bits/stdc++.h>
#define ll long long
#define INF 1000000005
#define MOD 1000000007
#define EPS 1e-10
#define rep(i,n) for(int i=0;i<(int)(n);++i)
#define rrep(i,n) for(int i=(int)(n)-1;i>=0;--i)
#define srep(i,s,t) for(int i=(int)(s);i<(int)(t);++i)
#define each(a,b) for(auto& (a): (b))
#define all(v) (v).begin(),(v).end()
#define len(v) (int)(v).size()
#define zip(v) sort(all(v)),v.erase(unique(all(v)),v.end())
#define cmx(x,y) x=max(x,y)
#define cmn(x,y) x=min(x,y)
#define fi first
#define se second
#define pb push_back
#define show(x) cout<<#x<<" = "<<(x)<<endl
#define spair(p) cout<<#p<<": "<<p.fi<<" "<<p.se<<endl
#define sar(a,n) cout<<#a<<":";rep(pachico,n)cout<<" "<<a[pachico];cout<<endl
#define svec(v) cout<<#v<<":";rep(pachico,v.size())cout<<" "<<v[pachico];cout<<endl
#define svecp(v) cout<<#v<<":";each(pachico,v)cout<<" {"<<pachico.first<<":"<<pachico.second<<"}";cout<<endl
#define sset(s) cout<<#s<<":";each(pachico,s)cout<<" "<<pachico;cout<<endl
#define smap(m) cout<<#m<<":";each(pachico,m)cout<<" {"<<pachico.first<<":"<<pachico.second<<"}";cout<<endl

using namespace std;

typedef pair<int,int> P;
typedef pair<ll,ll> pll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<double> vd;
typedef vector<P> vp;
typedef vector<string> vs;

const int MAX_N = 100005;

const int MAX_SIZE = 52;

int LCS(const string& a, const string& b){
    int n = (int)a.size(), m = (int)b.size();
    vector<int> x(n), y(m);
    rep(i,n){
        x[i] = a[i]-'a';
        if(x[i] < 0){
            x[i] = a[i]-'A'+26;
        }
    }
    rep(i,m){
        y[i] = b[i]-'a';
        if(y[i] < 0){
            y[i] = b[i]-'A'+26;
        }
    }
    vector<vector<int> > vec(MAX_SIZE);
    for(int j = m-1; j >= 0; --j){
        vec[y[j]].push_back(j);
    }
    vector<int> xs(n, INF);
    rep(i,n){
        rep(j,(int)vec[x[i]].size()){
            *lower_bound(xs.begin(),xs.end(),vec[x[i]][j]) = vec[x[i]][j];
        }
    }
    return lower_bound(xs.begin(),xs.end(),INF) - xs.begin();
}


int main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    int q;
    cin >> q;
    rep(i,q){
        string a,b;
        cin >> a >> b;
        cout << LCS(a,b) << "\n";
    }
    return 0;
}

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

int lcs(char X[], char Y[])
{
	int C[1001][1001];
	int m = strlen(X);
	int n = strlen(Y);
	int maxl = 0;

	for (int i = 1; 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 (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()
{
	ios::sync_with_stdio(false);
	cin.tie(0);

	char N1[1000], N2[1000];
	int q;

	cin >> q;
	for (int i = 0; i < q; i++)
	{
		cin >> N1 >> N2;
		cout << lcs(N1, N2);
	}
		
	return 0;                                                                            
}