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<cstdio>
#include<cstdlib>
#include<cmath>
#include<cstring>
#include<iostream>
#include<algorithm>
#include<queue>
#include<map>
#include<stack>

typedef long long ll;

using namespace std;

char a[1010],b[1010];
int maxlen[1010][1010];

int main() {
	ios::sync_with_stdio(false);
	
	
	while (cin>>a>>b){
		int len1 = strlen(a);
		int len2 = strlen(b);
		memset(maxlen,0,sizeof(maxlen));
		
		for(int i = 1 ; i<=len1 ; i++){
			for(int j = 1; j<=len2 ; j++){
				if(a[i-1] == b[j-1]){
					maxlen[i][j] = maxlen[i-1][j-1] + 1;
				}
				else{
					maxlen[i][j] = max( maxlen[i-1][j] , maxlen[i][j-1]);
				}
			}
		}
		cout<<maxlen[len1][len2]<<endl;
	} 
	return 0;
}

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

int lcs(string X, string Y) {
int max = 0;
int n = X.size();
int m = Y.size();
int dp[1000+1][1000+1];

X = ' '+X;
Y = ' '+Y;

for(int i = 1:i <= n; i++)
dp[i][0] = 0;

for(int i = 1; i <= m; i++)
dp[0][i] = 0;

for(int i = 1; i <= n; i++) {
for(int j = 1; j <= m; j++) {
if(X[i] == Y[j])
dp[i][j] = dp[i-1][j-1]+1;
else if(dp[i-1][j] > dp[i][j-1])
dp[i][j] = dp[i-1][j];
else
dp[i][j] = dp[i][j-1];

if(max < dp[i][j])
max = dp[i][j];
}
}

return max;
}

int main() {
int N;
cin >> N;

string X, Y;
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;
using ll = long long;
#define rep(i, n) for (int i = 0; i < n; i++)
#define repr(i, n) for (int i = n - 1; i >= 0; i--)

const int inf = 1000000007;
const int MOD = 1000000007;
const long long INF = 1000000000000000007;

int q;
int dp[1010][1010];

int solve(string x, string y)
{
    int n = x.length();
    int m = y.length();
    memset(dp, 0, sizeof(dp));
    for (int i = 0; i < n; i++)
    {
        for (int j = 0; j < m; j++)
        {
            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]);
            }
        }
    }
    return dp[n][m];
}

int main()
{
    cin >> q;
    for (int i = 0; i < q; i++)
    {
        string x, y;
        cin >> x >> y;
        cout << solve(x, y) << endl;
    }
}

C++: #include <iostream>
#include <string>

using namespace std;

int solve(string s1, string s2){
    int L[s1.size()+1][s2.size()+1];
    for(int i=0;i<=s1.size();i++){
        for(int j=0;j<=s2.size();j++){
            if(i<=0 || j<=0){
                L[i][j]=0;
            }
            else if(s1[i-1] == s2[j-1]){
                L[i][j] = 1 + L[i-1][j-1];
            }
            else{
                L[i][j] = max(L[i][j-1],L[i-1][j]);
            }
        }
    }
    return L[s1.size()][s2.size()];
}

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

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

void fnInput(vector<string>& rvsStrX, vector<string>& rvsStrY)
{
  int nMaxSiz;
  cin >> nMaxSiz;
  rvsStrX.resize(nMaxSiz);
  rvsStrY.resize(nMaxSiz);

  for (int i = 0; i < nMaxSiz; ++i)
  {
    cin >> rvsStrX[i] >> rvsStrY[i];
    rvsStrX[i] = ' ' + rvsStrX[i];
    rvsStrY[i] = ' ' + rvsStrY[i];
  }
}

int fnLngCmnSubseq(const vector<string>& cnrvsStrX, const vector<string>& cnrvsStrY)
{
  vector<vector<int>> vvnLcsDP;
  for (int i = 0; i < cnrvsStrX.size(); ++i)
  {
    int nMAXNX = cnrvsStrX[i].size();
    int nMAXNY = cnrvsStrY[i].size();
    vvnLcsDP.resize(nMAXNX, vector<int>(nMAXNY, 0));

    for (int nx = 1; nx < nMAXNX; ++nx)
      for (int ny = 1; ny < nMAXNY; ++ny)
        if (cnrvsStrX[i][nx] == cnrvsStrY[i][ny])
          vvnLcsDP[nx][ny] = vvnLcsDP[nx - 1][ny - 1] + 1;
        else
          vvnLcsDP[nx][ny] = max(vvnLcsDP[nx - 1][ny], vvnLcsDP[nx][ny - 1]);

    cout << vvnLcsDP[nMAXNX - 1][nMAXNY - 1] << endl;
  }
}

int main()
{
  cin.tie(0);
  ios::sync_with_stdio(false);
  vector<string> vsStrX, vsStrY;

  fnInput(vsStrX, vsStrY);
  fnLngCmnSubseq(vsStrX, vsStrY);
  return 0;
}

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

int lcs(string X, string Y) {
  int max = 0;
  int n = X.size();
  int m = Y.size();
  int dp[1000+1][1000+1];

  X = ' '+X;
  Y = ' '+Y;

  for(int i = 1;i <= n; i++)
    dp[i][0] = 0;

  for(int i = 1; i <= m; i++)
    dp[0][i] = 0;

  for(int i = 1; i <= n; i++) {
    for(int j = 1; j <= m; j++) {
      if(X[i] == Y[j])
	dp[i][j] = dp[i-1][j-1]+1;
      else if(dp[i-1][j] > dp[i][j-1])
	dp[i][j] = dp[i-1][j];
      else
	dp[i][j] = dp[i][j-1];

      if(max < dp[i][j])
	max = dp[i][j];
    }
  }

  return max;
}

int main() {
  int N;
  cin >> N;

  string X, Y;
  for (int i = 0; i < N; i++) {
    cin >> X >> Y;

    cout << lcs(X, Y) << endl;
  }
  return 0;
}

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

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    int n;
    cin>>n;
    for(int cnt=0;cnt<n;++cnt){
        int lngst_cmn[1001][1001]={0};
        string x,y;
        cin>>x>>y;

        for(size_t i=1;i<=x.size();++i){
            for(size_t j=1;j<=y.size();++j){
                string subx=x.substr(0,i),suby=y.substr(0,j);
                if(subx[i-1]==suby[j-1]){
                    lngst_cmn[i][j]=1+lngst_cmn[i-1][j-1];
                }
                else {
                    lngst_cmn[i][j]=(lngst_cmn[i-1][j]>lngst_cmn[i][j-1] ? lngst_cmn[i-1][j]:lngst_cmn[i][j-1]);
                }
            }
        }

        cout<<lngst_cmn[x.size()][y.size()]<<endl;
    }

}

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

#define FOR(i,a,b) for(int i=(a);i<(int)(b);i++)
#define rep(i,n) FOR(i,0,n)
#define ZERO(a) memset(a,0,sizeof(a))

int dp[1020][1020];

int lcs(string x, string y) {
    int n=x.size(), m=y.size();
    rep(i,n) rep(j,m) {
        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]);
    }
    return dp[n][m];
}

int main() {
    int q; cin >> q;
    rep(data,q) {
        ZERO(dp);
        string x, y;
        cin >> x >> y;
        int ans = lcs(x,y);
        cout << ans << endl;
    }
    return 0;
}