Go: package main

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

var (
	nstr   func() string
	stdout *bufio.Writer
)

func init() {
	nstr = newReadString(os.Stdin)
	stdout = bufio.NewWriter(os.Stdout)
}

func main() {
	defer stdout.Flush()

	n := nint()
	xList := make([]string, n)
	yList := make([]string, n)

	for i:=0;i<n ;i++  {
		xList[i] = nstr()
		yList[i] = nstr()
	}

	for i := 0; i<n	; i++  {
		fmt.Println(lcs(xList[i], yList[i]))
	}

}

func lcs(x string, y string) int{
	var m = len(x)
	var n = len(y)

	c := make([][]int, m+1)
	for i:= range c{
		c[i] = make([]int, n+1)
	}
	for i:=	1;i<=m ;i++  {
		for j:=1;j<=n ;j++  {
			if x[i-1] == y[j-1]{
				c[i][j] = c[i-1][j-1] + 1
			}else{
				c[i][j] = int(math.Max(float64(c[i-1][j]), float64(c[i][j-1])))
			}


		}
	}
	return c[m][n]

}


func newReadString(ior io.Reader) func() string {
	r := bufio.NewScanner(ior)
	r.Buffer(make([]byte, 1024), int(1e+11))
	r.Split(bufio.ScanWords)

	return func() string {
		if !r.Scan() {
			panic("Scan failed")
		}
		return r.Text()
	}
}

func nint64() int64 {
	i, err := strconv.ParseInt(nstr(), 0, 64)
	if err != nil {
		panic(err.Error())
	}
	return i
}

func nint() int {
	return int(nint64())
}

func getIntSlice(n int) []int {
	b := make([]int, n)
	for i := 0; i < n; i++ {
		b[i] = nint()
	}
	return b
}

func getStringSlice(n int) []string {
	b := make([]string, n)
	for i := 0; i < n; i++ {
		b[i] = nstr()
	}
	return b
}

func gcd(x, y int) int {
	if y == 0 {
		return x
	}
	return gcd(y, x%y)
}

func lcm(x, y int) int {
	return x * y / gcd(x, y)
}

func contains(s []int, e int) bool {
	for _, a := range s {
		if a == e {
			return true
		}
	}
	return false
}

func bin(i int, prefix bool) string {
	i64 := int64(i)

	if prefix {
		return "0b" + strconv.FormatInt(i64, 2)
	} else {
		return strconv.FormatInt(i64, 2)
	}
}

func strReverse(s string) string {
	runes := []rune(s)
	for i, j := 0, len(runes)-1; i < j; i, j = i+1, j-1 {
		runes[i], runes[j] = runes[j], runes[i]
	}

	return string(runes)
}

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

static const int N = 1000;

int max(int a, int b)
{
	if(a > b)
		return a;
	else 
		return b;
}
int lcs(string X, string Y)
{
	int c[N+1][N+1] = {0};
	int m = X.size();
	int n = Y.size();

	int max1 = 0;
	X = ' ' + X;
	Y = ' ' + Y;

	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]);
			}
			max1 = max(max1,c[i][j]);
		}
	}

	return max1;
}
int main()
{
	string a,b;
	int n;
	scanf("%d", &n);
	for(int i=0; i<n; i++)
	{
		cin >> a >> b;
		printf("%d\n",lcs(a,b));
	}

	return 0;
}

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

int lcs(string X, string Y) {
	int dp[1000 + 1][1000 + 1];
	int max = 0;
	X = ' ' + X;
	Y = ' ' + Y;
	for (unsigned int i = 1; i <= X.length() - 1; i++)
		dp[i][0] = 0;

	for (unsigned int i = 1; i <= Y.length() - 1; i++)
		dp[0][i] = 0;

	for (unsigned int i = 1; i <= X.length() - 1; i++) {
		for (unsigned int j = 1; j <= Y.length() - 1; j++) {
			if (X[i] == Y[i])
				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];

			max = (max < dp[i][j]) ? dp[i][j] : max;
        cout << "Hello" << endl;
		}
	}

	return max;
}

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

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

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

	return 0;
}

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

using namespace std;

int dp[1010][1010];

int main(void) {
    int q;
    string x, y;
    cin >> q;

    while (cin >> x >> y) {
        memset(dp, 0, sizeof dp);

        int xs = x.size(), ys = y.size();
        for (int i = 1; i <= xs; i++)
            for (int j = 1; j <= ys; 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], max(dp[i][j - 1], dp[i - 1][j - 1]));
            }
            
        cout << dp[xs][ys] << endl;
    }

    return 0;
}

C++: #include <bits/stdc++.h>
 
#define REP(i, n) for(int i=0;i<(int)(n);i++)
#define ALL(x) (x).begin(),(x).end()
const int INF = 1e9;
 
using namespace std;
int dp[1005][1005];
 
int main() {
    int n; cin >> n;
    REP(k, n){
        REP(i, 1005) REP(j, 1005) dp[i][j] = 0;
        string a, b;
        cin >> a >> b;
        REP(i, a.length()){
            string q = a.substr(i, 1);
            REP(j, b.length()){
                string t = b.substr(j, 1);
                if(q == t){
                    if(i == 0 || j == 0)
                        dp[i][j] = 1;
                    else
                        dp[i][j] = (dp[i-1][j] > dp[i][j-1]) ? max(dp[i-1][j-1] + 1, dp[i-1][j]) : max(dp[i-1][j-1] + 1, dp[i][j-1]);
                }
                else if (i != 0 && j != 0)
                    dp[i][j] = (dp[i-1][j] > dp[i][j-1]) ? dp[i-1][j] : dp[i][j-1];
                else if (i != 0)
                    dp[i][j] = dp[i-1][j];
                else
                    dp[i][j] = dp[i][j-1];
            }
        }
        cout << dp[a.length()-1][b.length()-1] << endl;
    }
    return 0;
}

C++: #include <iostream>
#include <iomanip>
#include <string>
#include <vector>
#include <algorithm>
#include <numeric>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <bitset>
#include <climits>
#define REP(i,n) for (int i=0;i<(n);i++)
#define FOR(i,a,b) for (int i=(a);i<(b);i++)
#define RREP(i,n) for (int i=(n)-1;i>=0;i--)
#define RFOR(i,a,b) for (int i=(a)-1;i>=(b);i--)
#define ll long long
#define ull unsigned long long
int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};
const int INF = 1e9;
const int MOD = 1e9 + 7;

using namespace std;
int dp[1000][1000];
int main(){
  cin.tie(0);
  ios::sync_with_stdio(false);
	int n;
	cin>>n;
	string s1,s2;
	while(n--){
		cin>>s1>>s2;
		REP(i,s1.size())dp[i][0] = 0;
		REP(i,s2.size())dp[0][i] = 0;
		FOR(i,1,s1.size()+1){
			FOR(j,1,s2.size()+1){
				if(s1[i] == s2[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[s1.size()][s2.size()] << 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 C[N+1][N+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 = C[i][j];
        }
    }
    return maxl;
}


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 <cstdio>
#include <cstring>
#include <algorithm>

using namespace std;

int main(){
  int N,X,Y;
  char x[1024],y[1024];
  int dp[1024][1024];
  scanf("%d",&N);
  while(N--){
    scanf("%s%s", x, y);
    X = strlen(x); Y = strlen(y);
    memset(dp, 0, sizeof dp);
    for(int i=0;i<X;i++){
      for(int j=0;j<Y;j++){
	if(x[i]==y[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]);
      }
    }
    printf("%d\n", dp[X][Y]);
  }
  return 0;
}