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 <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];
    int m = X.size();
    int n = Y.size();

    X = ' ' + X;
    Y = ' ' + Y;
    for (int i = 0; i <= m; i++) {
        C[i][0] = 0;
    }
    for (int i = 1; i <= n; i++) {
        C[0][i] = 0;
    }
    int maxl = -100;
    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 n;
    string X, Y;

    cin >> n;
    for (int i = 0; i < n; i++) {
        cin >> X >> Y;
        cout << lcs(X, Y) << endl;
    }

    return 0;
}

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

int DP[1010][1010];

int main(){
	int n;	cin>>n;
	for(int qi=0; qi<n; qi++){
		string s,t;		cin>>s>>t;
		int S=s.length(), T=t.length();
		s=" "+s;	t=" "+t;

		for(int i=0; i<=max(S,T); i++){
			DP[0][i]=DP[i][0]=0;
		}

		for(int i=1; i<=S; i++){
			for(int j=1; j<=T; j++){
				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]);
				}
			}
		}
		cout<<DP[S][T]<<endl;
	}

	return 0;
}

C++: #include <iostream>
#include <string>
#include <algorithm>
#include <functional>
#include <vector>
#include <stack>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <cstdio>
#include <cmath>
#include <tuple>
#include <iomanip>
#include <numeric>
#include <unordered_map>
#include <sstream>   
#include<limits.h>
#include<list>
#include <array>
using namespace std;
#define i64  long long
#define int  long long
 
#define I32_MAX 2147483647
#define I64_MAX 9223372036854775807
#define INF I64_MAX
#define MOD 1000000007
#define MEM_SIZE = 1e5+5;

template<typename T> void DEBUG(T e){std::cout << e << std::endl;}
template<class T> void DEBUG(string str, T e){std::cout <<str << ">>" << e << std::endl;}
template<typename T> void DEBUG(const std::vector<T>& v){for(const auto& e : v){ std::cout << e << " "; } std::cout << std::endl;}
template<typename T> void DEBUG(const std::vector<std::vector<T> >& vv){ for(const auto& v : vv){ DEBUG(v); } }
template <class T> void corner(bool flg, T hoge) {if (flg) {cout << hoge << endl; exit(0);}}



//BELOW
struct mint {
  int x; // typedef long long int;
  mint(int x=0):x((x%MOD+MOD)%MOD){}
  mint& operator+=(const mint a) {
    if ((x += a.x) >= MOD) x -= MOD;
    return *this;
  }
  mint& operator-=(const mint a) {
    if ((x += MOD-a.x) >= MOD) x -= MOD;
    return *this;
  }
  mint& operator*=(const mint a) {
    (x *= a.x) %= MOD;
    return *this;
  }
  mint operator+(const mint a) const {
    mint res(*this);
    return res+=a;
  }
  mint operator-(const mint a) const {
    mint res(*this);
    return res-=a;
  }
  mint operator*(const mint a) const {
    mint res(*this);
    return res*=a;
  }
  mint pow(int t) const {
    if (!t) return 1;
    mint a = pow(t>>1);
    a *= a;
    if (t&1) a *= *this;
    return a;
  }
 
  // for prime MOD
  mint inv() const {
    return pow(MOD-2);
  }
  mint& operator/=(const mint a) {
    return (*this) *= a.inv();
  }
  mint operator/(const mint a) const {
    mint res(*this);
    return res/=a;
  }
};
 
 
 
const int MAX = 510000;
 
long long fac[MAX], finv[MAX], inv[MAX];
// テーブルを作る前処理
void COMinit() {
    fac[0] = fac[1] = 1;
    finv[0] = finv[1] = 1;
    inv[1] = 1;
    for (int i = 2; i < MAX; i++){
        fac[i] = fac[i - 1] * i % MOD;
        inv[i] = MOD - inv[MOD%i] * (MOD / i) % MOD;
        finv[i] = finv[i - 1] * inv[i] % MOD;
    }
}
 
// 二項係数計算
long long COM(int n, int k){
    if (n < k) return 0;
    if (n < 0 || k < 0) return 0;
    return fac[n] * (finv[n - k] % MOD) % MOD;
}

//-----CODE------//


void solve(void)
{

  int Q;
  cin>>Q;
  for (int q = 0; q < Q; q++)
  {
    string A,B;
    cin>>A>>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(A[i] == B[j])
        {
          DP[i+1][j+1] = DP[i][j] + 1;
        }
        else
        {
          DP[i+1][j+1] = max(DP[i+1][j],DP[i][j+1]);
        }
      }      
    }
    
  cout<<DP[A.size()][B.size()]<<endl;
  }
  
  return; 
}


int32_t main(int32_t argc, const char *argv[])
{
  std::ios::sync_with_stdio(false);
  std::cin.tie(0);

  std::cout << std::fixed;
  std::cout << std::setprecision(9);
  solve();

 
  return 0;
}

C++: #include <iostream>
#include <sstream>
#include <vector>
#include <algorithm>
#include <string>
#include <functional>
#include <numeric>
#include <ctype.h>
#include <cstdlib>
#include <string.h>
#include <cmath>
#include <cstdio>
#include <map>
#include <queue>
#include <utility>
#define rep(i, n) for(int i = 0; i < n; i++);

using namespace std;

const int INF = 1000000007;
const double PI = acos(-1.0);
typedef long long llong;

const int N = 10000;

int search(string X, string Y)
{
	int c[1000 + 1][1000 + 1];
	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()
{
	string input1, input2;
	int n;
	cin >> n;
	for (int i = 0; i < n; i++)
	{
		cin >> input1 >> input2;
		cout << search(input1, input2) << endl;
	}

	return 0;
	

}

C++: #include <iostream>
#include <string>
#include <algorithm>
using namespace std;
static const int N=1000;
int kansuu(string X,string Y){
  int c[N+1][N+1];
  int m=X.size();
  int n=Y.size();
  int maxl=0;
  int i,j;
  X=' '+X;
  Y=' '+Y;
  for(i=0;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]);
      }
      maxl=max(maxl,c[i][j]);
    }
  }

  return maxl;
}
int main(void){
  string s1;
  string s2;
  int n,i;
  cin >> n;
  for(i=0;i<n;i++){
    cin >> s1 >> s2;
    cout << kansuu(s1, s2) << endl;
    //printf("\n");
  }
  return 0;
}