Go: package main

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

// I/O
type Scanner struct {
	sc *bufio.Scanner
}

func NewScanner() *Scanner {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	sc.Buffer(make([]byte, 1024), int(1e+9))
	return &Scanner{sc}
}

func (s *Scanner) nextStr() string {
	s.sc.Scan()
	return s.sc.Text()
}

func (s *Scanner) nextInt() int {
	i, e := strconv.Atoi(s.nextStr())
	if e != nil {
		panic(e)
	}
	return i
}

func (s *Scanner) nextFloat() float64 {
	f, e := strconv.ParseFloat(s.nextStr(), 64)
	if e != nil {
		panic(e)
	}
	return f
}

func (s *Scanner) nextRuneSlice() []rune {
	return []rune(s.nextStr())
}

func (s *Scanner) nextIntSlice(n int) []int {
	res := make([]int, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextInt()
	}
	return res
}

func (s *Scanner) nextFloatSlice(n int) []float64 {
	res := make([]float64, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextFloat()
	}
	return res
}

// Arithmetic
func max(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m < i {
			m = i
		}
	}
	return m
}

func min(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m > i {
			m = i
		}
	}
	return m
}

func abs(x int) int {
	if x > 0 {
		return x
	}
	return -x
}

func pow(x, y int) int {
	res := 1
	for i := 0; i < y; i++ {
		res *= x
	}
	return res
}

func ceil(a, b int) int {
	if a%b == 0 {
		return a / b
	} else {
		return a/b + 1
	}
}

// Sort
type RuneSlice []rune

func (a RuneSlice) Len() int           { return len(a) }
func (a RuneSlice) Less(i, j int) bool { return a[i] < a[j] }
func (a RuneSlice) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }

// Main
func main() {
	sc := NewScanner()
	wtr := bufio.NewWriter(os.Stdout)
	Q := sc.nextInt()
	for q := 0; q < Q; q++ {
		X, Y := sc.nextStr(), sc.nextStr()
		xLen, yLen := len(X), len(Y)
		dp := make([][]int, xLen+1)
		for i := 0; i <= xLen; i++ {
			dp[i] = make([]int, yLen+1)
		}
		for x := 0; x <= xLen; x++ {
			for y := 0; y <= yLen; y++ {
				if x == 0 || y == 0 {
					dp[x][y] = 0
				} else if X[x-1] == Y[y-1] {
					dp[x][y] = dp[x-1][y-1] + 1
				} else {
					dp[x][y] = max(dp[x-1][y], dp[x][y-1])
				}
			}
		}
		fmt.Fprintln(wtr, dp[xLen][yLen])
	}

	wtr.Flush()
}

C++: #include <stdio.h>
#include <iostream>
using namespace std;
const int N=1e3+10;
int max(int a,int b){return a>b?a:b;}
int main(){
    int n,dp[N][N];
    string a,b;
    scanf("%d",&n);
    while(n--){
        cin>>a>>b;
        a='!'+a;
        b='@'+b;
        for(int i=0;i<a.size();i++)dp[i][0]=0;
        for(int i=0;i<b.size();i++)dp[0][i]=0;
        for(int i=1;i<a.size();i++)for(int j=1;j<b.size();j++){
            dp[i][j]=max(dp[i-1][j],dp[i][j-1]);
            if(a[i]==b[j])dp[i][j]=max(dp[i][j],dp[i-1][j-1]+1);
        }
        printf("%d\n",dp[a.size()-1][b.size()-1]);
    }
}

C++: 
#include<iostream>

int main(){
  int n;
  std::string x,y;
  std::cin>>n;
  int a[1000][1000];
  int b[n];

  for(int i=0;i<n;i++){
    std::cin>>x;
    std::cin>>y;
    for(int j=0;j<1000;j++){
      for(int k=0;k<1000;k++){
	a[j][k]=0;
      }
    }
    for(int j=0;j<x.size();j++){
      for(int k=0;k<y.size();k++){
	if(x[j]==y[k]){
	  a[j][k]=a[j-1][k-1]+1;
	}else{
	  if(a[j-1][k]>a[j][k-1]){
	    a[j][k]=a[j-1][k];
	  }else{
	    a[j][k]=a[j][k-1];
	  }
	}
      }
    }
    b[i]=a[x.size()-1][y.size()-1];
  }

  for(int i=0;i<n;i++){
  std::cout<<b[i]<<"\n";
  }

  return 0;
}

C++: #include <iostream>
#include <cstring>
#include <string>
#include <algorithm>
using namespace std;
const int MAX = 1000+5;
int DP[MAX][MAX];
string s1,s2;
int LCS(){
	memset(DP,0,sizeof(DP));
	int l1 = s1.size(),l2 = s2.size();
	int maxl = 0;
	s1 = ' '+s1;
	s2 = ' '+s2;
	for(int i = 1;i <= l1;i++)	DP[i][0] = 0;
	for(int j = 1;j <= l2;j++)	DP[0][j] = 0;
	for(int i = 1;i <= l1;i++){
		for(int j = 1;j <= l2;j++){
			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]);
			maxl = max(DP[i][j],maxl);
		}
	}
	return maxl;
}
int main(int argc, char const *argv[])
{
	int T;
	cin >> T;
	while(T--){
		cin >> s1 >> s2;
		cout << LCS() << endl;
	}
	return 0;
}

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

int main(void){
    int L[1010][1010]={{0}}, Z;
    string X, Y;
    int q;
    
    cin >> q;
    for(int k=0; k<q; k++){
        cin >> X;
        cin >> Y;
    
    for(int i=0; i<X.size(); i++){
        for(int j=0; j<Y.size(); j++){
            if(i==0 || j==0){
                if(X[i]==Y[j])  L[i][j]=1;
                else            L[i][j]=0;
            }
            else if(X[i] == Y[j])    L[i][j]=1+L[i-1][j-1];
            else L[i][j]=max(L[i][j-1], L[i-1][j]);
            Z=L[i][j];
        }
    }
    
    cout << Z << endl;
    
    }
    return 0;
}

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

#define MAX_N 1000
#define MAX_M 1000

int n;
string s, t;

int dp[MAX_N + 1][MAX_M + 1];

void solve(){
	for(int i = 0; i < s.size(); i++){
		for(int j = 0; j < t.size(); j++){
			if(s[i] == t[j]){
				dp[i + 1][j + 1];
					dp[i + 1][j + 1] = dp[i][j] + 1;
				} else {
					dp[i + 1][j + 1] = max(dp[i][j], dp[i + 1][j]);
				}
			}
		}
		printf("%d\n", dp[s.size()][t.size()]);
}

int main(){
	cin >> n;
	for(int i = 0; i < n; i++){
		cin >> s >> t;
		solve();
	}
}

C++: #define _CRT_SECURE_NO_WARNINGS

#include <stdio.h>
#include <iostream>
#include <string.h>
using namespace std;

class LCS{
private:	
	char x[1000 + 1];
	char y[1000 + 1];
	int lcs[1000][1000];
public:
	LCS(const char x[], const char y[]);
	int calcLCS();
	int calcLCS(int i, int j);
};

LCS::LCS(const char x[], const char y[])
{
	strcpy(this->x, x);
	strcpy(this->y, y);
	for (int i = 0; (this->x)[i] != '\0'; i++) {
		for (int j = 0; (this->y)[j] != '\0'; j++) {
			lcs[i][j] = -1;
		}
	}
}

int LCS::calcLCS(){
	int i, j;
	for (i = 0; ; i++) {
		if (x[i + 1] == '\0') break;
	}
	for (j = 0; ; j++) {
		if (y[j + 1] == '\0') break;
	}
	return calcLCS(i, j);
}

int LCS::calcLCS(int i, int j)
{
	if (i < 0 || j < 0) return 0;

	if (lcs[i][j] != -1) return lcs[i][j];

	if (x[i] == y[j]) lcs[i][j] = calcLCS(i - 1, j - 1) + 1;
	else lcs[i][j] = max(calcLCS(i, j - 1), calcLCS(i - 1, j));
	return lcs[i][j];
}

int main(void)
{
	int q;
	cin >> q;
	cin.ignore(1);
	for (int i = 0; i < q; i++) {
		char x[1000 + 1] = "\0";
		char y[1000 + 1] = "\0";
		cin.getline(x, 1000 + 1);
		cin.getline(y, 1000 + 1);
		LCS *lcs = new LCS(x, y);
		cout << lcs->calcLCS() << endl;
		delete lcs;
	}

	return 0;
}

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

int n, m;
char s[1000], t[1000];
int dp[1001][10001];

int main(void){
    cin >> n;
    for(int i=0;i<n;i++){
        cin >> s;
        cin >> t;
        int sizeofs = strlen(s);
        int sizeoft = strlen(t);
        for(int i=0;i<sizeofs;i++){
            for(int j=0;j<sizeoft;j++){
                if(s[i] == t[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]);
                }
            }
        }
        cout << dp[sizeofs][sizeoft] <<endl;
    }

    return 0;
}