Go: package main

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

const (
	initialBufSize = 100000
	maxBufSize     = 1000000
)

var sc *bufio.Scanner

func initScanner(r io.Reader) *bufio.Scanner {
	buf := make([]byte, initialBufSize)

	sc := bufio.NewScanner(r)
	sc.Buffer(buf, maxBufSize)
	sc.Split(bufio.ScanWords) // bufio.ScanLines
	return sc
}

func main() {
	sc = initScanner(os.Stdin)
	resolve()
}

func resolve() {
	n := scanInt(sc)
	results := []int{}
	for i := 0; i < n; i++ {
		results = append(results, resolveInstance())
	}
	for _, v := range results {
		fmt.Println(v)
	}
	return
}

func resolveInstance() int {
	x, y := scanString(sc), scanString(sc)
	lx, ly := len(x), len(y)
	dp := make([][]int, lx+1)
	dp[0] = make([]int, ly+1)
	for i := 1; i <= lx; i++ {
		dp[i] = make([]int, ly+1)
		dp[i][0] = dp[i-1][0]
		for j := 1; j <= ly; j++ {
			dp[i][j] = dp[i-1][j]
			if dp[i][j] < dp[i][j-1] {
				dp[i][j] = dp[i][j-1]
			}
			if x[i-1] == y[j-1] {
				cL := dp[i-1][j-1] + 1
				if dp[i][j] < cL {
					dp[i][j] = cL
				}
			}
		}
	}
	return dp[lx][ly]
}

const (
	remove = 0 + iota
	match
)

// snip-scan-funcs
func scanInt(sc *bufio.Scanner) int {
	sc.Scan()
	i, _ := strconv.Atoi(sc.Text())
	return int(i)
}
func scanString(sc *bufio.Scanner) string {
	sc.Scan()
	return sc.Text()
}

C++: #include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;
typedef pair<ll, ll> pll;
typedef vector<ld> vd;
typedef vector<ll> vll;
typedef vector<string> vstr;
typedef vector<vector<ll>> vvll;
typedef vector<pair<ll, ll>> vpll;
typedef priority_queue<ll, vector<ll>, greater<ll>> spqll;  // 小さい順に取り出し
typedef priority_queue<ll, vector<ll>, less<ll>> bpqll;     // 大きい順に取り出し

#define REP(i, n) for (ll i = 0; i < (ll)(n); i++)
#define FOR(i, a, b) for (ll i = (ll)a; i < (ll)b; i++)
#define IREP(i, v) for (auto i = (v).begin(); i != (v).end(); i++)
#define FI first
#define SE second
#define MP make_pair
#define MT make_tuple
#define PB push_back
#define TS to_string
#define NP next_permutation
#define ALL(v) (v).begin(), (v).end()
#define SZ(x) (ll) x.size()
#define SP(x) setprecision((ll)x)


ll INF = 1e9;
ll NIL = -1;
ll MOD = 1000000007;
ll LINF = 1e18;
ld EPS = 1e-9;
ld PI = M_PI;
vll dx = {1, 0, -1, 0, 1, -1, -1, 1};
vll dy = {0, 1, 0, -1, 1, 1, -1, -1};
ll gcd(ll a, ll b) { return b ? gcd(b, a % b) : a;} //最大公約数
ll lcm(ll a, ll b) { return a / gcd(a, b) * b;}     //最小公倍数

void yes(){ cout << "yes" << endl;}
void no(){ cout << "no" << endl;}

//-----------------------------------------
int dp[1000+10][1000+10];



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

  int n;
  cin >> n;
  for(int i=0;i<n;i++){
    string s, t;
    cin >> s >> t;
    int ss = s.size();
    int st = t.size();
    for(int i=0;i<=ss;i++){
      for(int j=0;j<=st;j++){
        if(i==0 || j==0) dp[i][j] = 0;
        else dp[i][j] = -1;
      }
    }
    for(int i=1;i<=ss;i++){
      for(int j=1;j<=st;j++){
        if(s[i-1] == t[j-1]) dp[i][j] = dp[i-1][j-1] + 1;
        else dp[i][j] = max(dp[i-1][j],dp[i][j-1]);
      }
    }
    cout << dp[ss][st] <<endl;
  }

  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
 
#define rep(i, n) for (int i = (int)(0); i < (int)(n); ++i)
#define reps(i, n) for (int i = (int)(1); i <= (int)(n); ++i)
#define rrep(i, n) for (int i = ((int)(n)-1); i >= 0; i--)
#define rreps(i, n) for (int i = ((int)(n)); i > 0; i--)
#define irep(i, m, n) for (int i = (int)(m); i < (int)(n); ++i)
#define ireps(i, m, n) for (int i = (int)(m); i <= (int)(n); ++i)
#define FOR(e, c) for (auto &e : c)
#define SORT(v, n) sort(v, v + n);
#define vsort(v) sort(v.begin(), v.end());
#define rvisort(v) sort(v.begin(), v.end(), greater<int>());
#define all(v) v.begin(), v.end()
#define mp(n, m) make_pair(n, m);
#define cout(d) cout<<d<<endl;
#define coutd(d) cout<<std::setprecision(10)<<d<<endl;
#define cinline(n) getline(cin,n);
#define replace_all(s, b, a) replace(s.begin(),s.end(), b, a);
#define rv(s) reverse(s.begin(),s.end());
 
using ll = long long;
using vi = vector<int>;
using vvi = vector<vi>;
using vll = vector<ll>;
using vvll = vector<vll>;
using pii = pair<int, int>;
using vpii = vector<pii>;
using vs = vector<string>;
using vd = vector<double>;
using ul = unsigned long;
 
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 GCD(int a, int b) { return b ? GCD(b, a%b) : a; }

int main()
{
  cin.tie( 0 );
  ios::sync_with_stdio( false );
  
  int q;cin>>q;
  
  rep(ki,q){
    string x,y;
    cin>>x>>y;
    int m=x.size();
    int n=y.size();
    int dp[1001][1001];
    
    rep(i,m)dp[i][0]=0;
    rep(i,n)dp[0][i]=0;
    
    for(int i=1;i<=m;i++){
      for(int j=1;j<=n;j++){
        if(x[i-1]==y[j-1]){
          dp[i][j]=dp[i-1][j-1]+1;
        }else{
          dp[i][j]=max(dp[i-1][j],dp[i][j-1]);
        }
      }
    }
    
    cout(dp[m][n]);
  }
}

C++: //ALDS1_10_C
#include <iostream>
#include <string>
#include <vector>
using namespace std;

int main(){
	string X, Y;
	int q;
	vector<vector<int> > dp;

	cin>>q;
	for(int i=0;i<q;i++){
		cin>>X;
		cin>>Y;

		dp.resize(X.length()+1);
		for(int j=0;j<=X.length();j++)
			dp[j].resize(Y.length()+1);

		for(int j=0;j<=X.length();j++)
			dp[j][0] = 0;
		for(int k=0;k<=Y.length();k++)
			dp[0][k] = 0;

		for(int j=1;j<=X.length();j++){
			for(int k=1;k<=Y.length();k++){
				if(X[j-1] == Y[k-1])
					dp[j][k] = dp[j-1][k-1] + 1;
				else
					dp[j][k] = max(dp[j-1][k], dp[j][k-1]);
			}
		}

		cout<<dp[X.length()][Y.length()]<<endl;
	}

	return 0;
}

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

static const int N = 1000;

int lcs(string X, string Y) {
	int i, j, c[N+1][N+1];
	int m = X.size(), n = Y.size(), max1 = 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-1][j], c[i][j-1]);
			max1 = max(max1, c[i][j]);
		}
	}
	return max1;
}

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

	return 0;
}

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

int solve(string s, string t) {
  int ss = s.size();
  int tt = t.size();
  vector<vector<int> > dp(ss+1, vector<int>(tt+1, 0));
  s.insert(0, " ");
  t.insert(0, " ");
  
  int ret = 0;
  rep(i, 1, ss+1) {
    rep(j, 1, tt+1) {
      if(s[i] == t[j])
        dp[i][j] = dp[i-1][j-1] +1;
      else
        dp[i][j] = max(dp[i-1][j], dp[i][j-1]);
      ret = max(ret, dp[i][j]);
    }
  }
  return ret;
}

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  
  int q;
  cin >> q;
  rep(aa, 0, q) {
    string x, y;
    cin >> x >> y;
    cout << solve(x, y) << "\n";
  }
}

C++: #if 0
PDFに記載されている方針がわかりやすかったので、比較的簡単に解くことができた。
#endif

#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;

int Q;
int L[1000+10][1000+10];

int main() {
  cin >> Q;
  string X, Y;
  for (int i = 0; i < Q; i++) {
    for (int j = 0; j < 1000+10; j++) {
      L[0][j] = 0; L[j][0] = 0;
    }
    cin >> X >> Y;
    for (int x = 1; x <= X.length(); x++) {
      for (int y = 1; y <= Y.length(); y++) {
        if (X[x-1] == Y[y-1])
          L[x][y] = L[x-1][y-1] + 1;
        else
          L[x][y] = max(L[x-1][y], L[x][y-1]);
      }
    }
    cout << L[X.length()][Y.length()] << endl;
  }
}