Go: package main

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

func getScanner(fp *os.File) *bufio.Scanner {
	scanner := bufio.NewScanner(fp)
	scanner.Split(bufio.ScanWords)
	scanner.Buffer(make([]byte, 500001), 500000)
	return scanner
}

func getNextString(scanner *bufio.Scanner) string {
	scanner.Scan()
	return scanner.Text()
}

func getNextInt(scanner *bufio.Scanner) int {
	i, _ := strconv.Atoi(getNextString(scanner))
	return i
}

func main() {
	fp := os.Stdin
	if len(os.Args) > 1 {
		fp, _ = os.Open(os.Args[1])
	}

	scanner := getScanner(fp)
	writer := bufio.NewWriter(os.Stdout)

	n := getNextInt(scanner)
	for i := 0; i < n; i++ {
		x := getNextString(scanner)
		y := getNextString(scanner)

		fmt.Fprintln(writer, lcs(x, y))
	}

	writer.Flush()
}

func lcs(x, y string) int {
	lx := len(x)
	ly := len(y)
	dp := make([][]int, lx+1)
	for i := 0; i <= lx; i++ {
		dp[i] = make([]int, ly+1)
	}
	for i := 0; i < lx; i++ {
		for ii := 0; ii < ly; ii++ {
			if x[i] == y[ii] {
				dp[i+1][ii+1] = dp[i][ii] + 1
				continue
			}
			dp[i+1][ii+1] = dp[i][ii+1]
			if dp[i+1][ii] > dp[i+1][ii+1] {
				dp[i+1][ii+1] = dp[i+1][ii]
			}
		}
	}
	return dp[lx][ly]
}

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

using namespace std;
using ll = long long;

void init();
void solve();

#define rep(i, a) for (int i = 0; i < (int) (a); i++)
#define reps(i, a, b) for (int i = (int) (a); i < (int) (b); i++)
#define rrep(i, a) for (int i = (int) a-1; i >= 0; i--)
#define rreps(i, a, b) for (int i = (int) (a)-1; i >= (int) (b); i--)
#define MP(a, b) make_pair((a), (b))
#define PB(a) push_back((a))
#define all(v) (v).begin(), (v).end()
#define PRINT(f) if((f)){cout << (TRUE__) << endl;}else{cout << FALSE__ << endl;}
#define TRUE__  "Yes"
#define FALSE__ "No"
#define PERM(v) next_permutation(all(v))
#define UNIQUE(v) sort(all(v));(v).erase(unique(all(v)), v.end())
#define CIN(type, x) type x;cin >> x

#ifdef LOCAL
#define lcout(a) cout << a
#define lcoutln(a) cout << a << endl
#define lcerr(a) cerr << a
#define lcerrln(a) cerr << a << endl
#else
#define lcout(a) 
#define lcoutln(a) 
#define lcerr(a) 
#define lcerrln(a) 
#endif
#define MOD 1000000007

signed main()
{
	init();
	solve();
}

int q, xl, yl;
string x, y;

void init()
{
	cin >> q;
}

int dp[1010][1010];

void reset()
{
	rep(i, 1010) {
		dp[i][0] = 0;
		dp[0][i] = 0;
	}
}


void solve()
{
	rep(i, q) {
		cin >> x >> y;
		xl = x.length();
		yl = y.length();
		reps(i, 1, xl+1) reps(j, 1, yl+1) {
			if (x[i-1] == y[j-1]) dp[i][j] = dp[i-1][j-1] + 1;
			else dp[i][j] = max(dp[i][j-1], dp[j-1][i]);
		}
		cout << dp[xl][yl] << endl;
		reset();
	}
}

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

int main(){
  int INF=-10000;

  int d;
  int i,j,k;
  cin>>d;
  vector<int> ans(d);
  for(k=0;k<d;k++){
    string a,b;
    cin>>a>>b;

    vector<vector<int>> dp(a.size()+1,vector<int>(b.size()+1,0));
    dp.at(0).at(0)=0;
    for(i=0;i<a.size();i++){
      // cout<<"i "<<i<<endl;
      for(j=0;j<b.size();j++){
        // cout<<"j "<<j<<endl;
        if(a.at(i)==b.at(j)){
          dp.at(i+1).at(j+1)=dp.at(i).at(j)+1;
        } else{
          dp.at(i+1).at(j+1)=max(dp.at(i).at(j+1),dp.at(i+1).at(j));
        }
      }
    }

    ans.at(k)=dp.at(a.size()).at(b.size());
}

for(k=0;k<d;k++)
cout<<ans.at(k)<<endl;

}

C++: #include<iostream>
#include<algorithm>
using namespace std;
int dp[1001][1001];
string s,t;
int n,m,a,ans;
int main(){
  cin>>a;
  for(int b=0;b<a;b++){
    cin>>s>>t;
    for(int i=0;i<=1000;i++)
      for(int j=0;j<=1000;j++)
	dp[i][j]=0;
    m=s.size();
    n=t.size();
    ans=0;
    for(int i=1;i<=m;i++){
      for(int j=1;j<=n;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[m][n]<<endl;
  }
  return 0;
}

C++: 
#include <iostream>
#include <algorithm>
#include <iomanip>
#include <vector>
#include <string>

using namespace std;

int q;
int main() {
	cin >> q;
	for (int i = 0; i < q; i++) {
		string x, y;
		cin >> x >> y;
		int m = x.size();
		int n = y.size();
		x = ' ' + x;
		y = ' ' + y;
		int maxl = 0;
		int c[1001][1001];
		c[0][0] = 0;
		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][j - 1], c[i - 1][j]);
				}
				maxl = max(maxl, c[i][j]);
			}
		}
		cout << maxl << endl;
	}
	return 0;
}

C++: #include<iostream>
#include<cmath>
#include<algorithm>
#include<string>
#include<vector>
#include<stack>
#include<queue>
#include<set>
#include<map>
#include<iomanip>
#include<bitset>
using namespace std;
typedef long long ll;
typedef pair<ll,ll> P;
typedef pair<ll,P> P1;
typedef pair<P,P> P2;
#define pu push
#define pb push_back
#define mp make_pair
#define eps 1e-7
#define INF 1000000000
#define fi first
#define sc second
#define rep(i,x) for(ll i=0;i<x;i++)
#define repn(i,x) for(ll i=1;i<=x;i++)
#define SORT(x) sort(x.begin(),x.end())
#define ERASE(x) x.erase(unique(x.begin(),x.end()),x.end())
#define POSL(x,v) (lower_bound(x.begin(),x.end(),v)-x.begin())
#define POSU(x,v) (upper_bound(x.begin(),x.end(),v)-x.begin())

const int MAX = 510000;
const int MOD = 1000000007;

int main(){
  ll N; cin >> N;
  vector<string> v(2 * N);
  rep(i, 2 * N) cin >> v[i];
  rep(loop, N){
    string s,t;
    s = v[2 * loop]; t = v[2 * loop + 1];
    ll a = s.size(), b = t.size();
    vector<vector<ll> > dp(a + 1 , vector<ll>(b + 1, 0) );
    rep(i,a){
      rep(j,b){
        if(s[i] == t[j]){
          dp[i + 1][j + 1] = max(dp[i + 1][j] , max(dp[i][j + 1], dp[i][j] + 1) );
        }
        else{
          dp[i + 1][j + 1] = max(dp[i + 1][j] , dp[i][j + 1]);
        }
      }
    }
    /*
    rep(i,a + 1){
      rep(j,b + 1){
        cout << dp[i][j] << " ";
      }
      cout << endl;
    }
    */
    cout << dp[a][b] << endl;
  }
}

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

static const int N=1000;

int Lcs(string X, string Y){
  int c[N+1][N+1], LMAX=0;;
  int m=X.size(), n=Y.size();

  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]);
      }
      LMAX=max(LMAX, c[i][j]);
    }
  }

  return LMAX;
}

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

  return 0;
}

C++: #include <iostream>
#include <string>
#include <algorithm>
using namespace std;
#define MAX 1000

int c[MAX + 1][MAX + 1];

int lcs(string x, string y) {
	int m = x.size();
	int n = y.size();
	int maxl = 0;
	x = ' ' + x;
	y = ' ' + y;
	for (int i = 0; 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][j - 1], c[i - 1][j]);
			}
			maxl = max(maxl, c[i][j]);
		}
	}
	return maxl;
}

int main()
{
	int q;
	cin >> q;
	string x, y;
	int l[150] = { 0 };

	for (int i = 0; i < q; i++) {
		cin >> x >> y;
		l[i] = lcs(x, y);
	}
	for (int i = 0; i < q; i++) {
		cout << l[i] << endl;
	}
	return 0;
}