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>
#define rep(i, n) for(int i=0; i<(n); ++i)
#define rep2(i, s, n) for(int i=s; i<(n); ++i)
#define ALL(v) (v).begin(), (v).end()

using namespace std;

typedef long long ll;

static const int INTINF = (2147483647 >> 1); // 10^9 + 5000
static const ll LLINF = (9223372036854775807 >> 1);
static const int MAX = 1e5+1;
static const ll MOD = 1e9+7;

namespace Kunitaka{
    template<
        typename TYPE,
        std::size_t SIZE
    >
    std::size_t array_length(const TYPE (&array)[SIZE])
    {
        return SIZE;
    }
}
using namespace Kunitaka;
namespace Printer{
    void br(){
        cout << endl;
    }

    void loop_cnt(int i){
        cout << "i = " << i << endl;
    }

    void loop_cnt(int i, int j){
        cout << "i = " << i << ", " << "j = " << j << endl;
    }

    template<class T>
    void print(T x){
        cout << x << endl;
    }

    template<class T, class S>
    void print(T x, S y){
        cout << x << "," << y << endl;
    }

    template<class T, class S, class U>
    void print(T x, S y, U z){
        cout << x << "," << y << "," << z << endl;
    }

    template<class T, class S>
    void print(pair<T, S> p){
        cout << p.first << ", " << p.second << endl;
    }

    template<
        typename TYPE,
        std::size_t SIZE
    >
    void print(const TYPE (&array)[SIZE]){
        int lim = array_length(array);
        for(int i=0; i<lim; i++){
            if(i) cout << " ";
            cout << array[i];
        }
        cout << endl;
    }

    template<class S>
    void print(vector<S> v){
        for(int i=0; i<v.size(); i++){
            if(i) cout << " ";
            cout<< v[i];
        }
        cout << endl;
    }

    template<class S>
    void print(vector<vector<S> > vv){
        for(int i=0; i<vv.size(); i++){
            for(int j=0; j<vv[i].size(); j++){
                if(j) cout << " ";
                cout << vv[i][j];
            }
            cout << endl;
        }
    }

    void yesno(bool x){
        if(x) cout << "Yes" << endl;
        else cout << "No" << endl;
    }
};
using namespace Printer;

int main(int argc, const char * argv[]) {
    //提出時、消す----//

    //--------------//


    // input
    cout << fixed << setprecision(10);
    int N; cin >> N;
    rep(i, N){
        string S, T; cin >> S >> T;
        vector<vector<int> > dp(T.size()+1, vector<int>(S.size()+1));
        int ans = 0;
        rep2(j, 1, T.size()+1){
            rep2(k, 1, S.size()+1){
                if(T[j-1] == S[k-1]){
                    dp[j][k] = dp[j-1][k-1] + 1;
                }
                else{
                    dp[j][k] = max(dp[j][k-1], dp[j-1][k]);
                }
                ans = max(ans, dp[j][k]);
            }
        }
        print(ans);
    }
    
    return 0;
}

C++: #include <bits/stdc++.h>
#define REP(i, n) for(int i = 0;i < n;i++)
#define REPR(i, n) for(int i = n;i >= 0;i--)
#define FOR(i, m, n) for(int i = m;i < n;i++)
#define FORR(i, m, n) for(int i = m;i >= n;i--)
#define SORT(v, n) sort(v, v+n);
#define VSORT(v) sort(v.begin(), v.end());
#define VRSORT(v) sort(v.rbegin(), v.rend());//vectorの降順ソート
#define ll long long
#define pb(a) push_back(a)
#define INF 1000000000
using namespace std;
typedef pair<int, int> P;
typedef pair<ll, ll> LP;
typedef pair<int, P> PP;
typedef pair<ll, LP> LPP;

int dy[]={0, 0, 1, -1, 0};
int dx[]={1, -1, 0, 0, 0};

int lcs(string X,string Y){
    int c[1050][1050];
    int m = X.size();
    int n = Y.size();
    int maxl = 0;
    X = ' ' + X;
    Y = ' ' + Y;
    REP(i,m+1) 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 c[i][j] = max(c[i-1][j],c[i][j-1]);
            maxl = max(maxl,c[i][j]);
        }
    }
    return maxl;
}
int main(){
  cin.tie(0);
  ios::sync_with_stdio(false);
  int q;
  cin >> q;
  while(q--){
      string a,b;
      cin >> a >> b;
      cout << lcs(a,b) << endl;
  }
}

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

int q, dp[1001][1001], xnum, ynum;
char x[1001], y[1001];

int main() {
  scanf("%d", &q);
  for (int i = 0; i < q; i++) {
    scanf("%s%s", x, y);
    xnum = ynum = 0;
    while (x[xnum] != 0) xnum++;
    while (y[ynum] != 0) ynum++;
    for (int j = 0; j <= xnum; j++) for (int k = 0; k <= ynum; k++) dp[i][j] = 0;
    for (int j = 0; j < xnum; j++) for (int k = 0; k < ynum; k++) {
      if (x[j] == y[k]) dp[j+1][k+1] = dp[j][k] + 1;
      else dp[j+1][k+1] = max(dp[j+1][k], dp[j][k+1]);
    }
    printf("%d\n", dp[xnum][ynum]);
  }
}

C++: #include <iostream>
#include <string>
#include <algorithm>
    using namespace std;
int lcs(string x,string y){
    int c[1010][1010];
    int m = x.size();
    int n = y.size();
    int maxl=0;
    x = ' '+x;
    y = ' '+y;
    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 c[i][j] = max(c[i-1][j], c[i][j-1]);
            maxl = max(maxl, c[i][j]);
        }
        
    }
    return maxl;
}
int main(){
    int q;
    string x;
    string y;
    scanf("%d",&q);
    for (int i=0; i<q; i++) {
        cin>>x>>y;
        cout<<lcs(x, y)<<endl;
    }
    return 0;
}