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 <bits/stdc++.h>

using namespace std;

#define FOR(i,s,e) for((i)=(s);(i)<(int)(e);(i)++)
#define REP(i,e) FOR(i,0,e)

#define all(o) (o).begin(), (o).end()
#define psb(x) push_back(x)
#define mp(x,y) make_pair((x),(y))

typedef long long ll;
typedef pair<int, int> PII;

const double EPS = 1e-10;

const int N = 1000;
char s[N+1], t[N+1];
int ls, lt;
int q;
int dp[N+1][N+1];
//dp[i][j] = s[0]...s[i+1]??¨t[0]...t[j+1]???LCS
//(1<=i<=ls, 1<=j<=lt)

int main() {
  int i, j, k;
  scanf("%d ", &q);
  for (k=0; k<q; k++) {
    ls = lt = 0;
    memset(s, 0, sizeof(s)), scanf("%s ", s);
    memset(t, 0, sizeof(t)), scanf("%s ", t);
    while (s[ls]) ls++;
    while (t[lt]) lt++;

    memset(dp, 0, sizeof(dp));
    for (i=1; i<=ls; i++)
      for (j=1; j<=lt; 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]);
      }

    printf("%d\n", dp[ls][lt]);
  }

  return 0;
}

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

using namespace std;

int lcs (string x, string y) {

    int m, n, c[1001][1001], i, j, maxl = 0;

    m = x.size();
    n = y.size();

    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 () {

    int N, i;
    string x, y;

    cin >> N;

    for (i = 0; i < N; i++) {
        cin >> x >> y;
        cout << lcs (x, y) << endl;

    }

    return 0;

}

C++: #include <iostream>
#include <vector>
#include <string>
#include <cmath>
#include <algorithm>
#include <queue>
#include <unordered_map>

#define rep(i, n) for(int i = 0; i < (int)(n); i++)
typedef long long ll;

using namespace std;

template<class T>
vector<T> make_vec(size_t a){
    return vector<T>(a);
}
template<class T, class... Ts>
auto make_vec(size_t a, Ts... ts){
    return vector<decltype(make_vec<T>(ts...))>(a, make_vec<T>(ts...));
}

void solve(string s1, string s2) {
    vector<int> dp[s1.size() + 1];
    vector<int> tmp(s2.size() + 1, 0);
    rep(i, s1.size() + 1) {
        dp[i] = tmp;
    }
    rep(i, s1.size() + 1) {
        rep(j, s2.size() + 1) {
            if(i == 0 || j == 0) {
                continue;
            } else {
                if(s1[i-1] == s2[j-1]) {
                    dp[i][j] = dp[i-1][j-1] + 1;
                }
                dp[i][j] = max(dp[i][j], max(dp[i-1][j], dp[i][j-1]));
            }
        }
    }
    // rep(i, s1.size() + 1) {
    //     rep(j, s2.size() + 1) {
    //         cout << dp[i][j] << " ";
    //     }
    //     cout << endl;
    // }
    cout << dp[s1.size()][s2.size()] << endl;
}

int main(){
    int n; cin >> n;
    rep(i, n) {
        string s1, s2; cin >> s1 >> s2;
        solve(s1, s2);
    }
}

C++: #include <bits/stdc++.h>
using namespace std;
int q;
string x, y;
int m, n;
int a[1000][1000];
int main()
{
	cin >> q;
	for(int i=0; i<q; i++)
	{
		cin >> x >> y;
		m=x.size();
		n=y.size();
		if(x[0]==y[0])
		{
			a[0][0]=1;
		}
		else
		{
			a[0][0]=0;
		}
		for(int j=1; j<m+n-1; j++)
		{
			if((j<n)&&((x[0]!=y[j])&&(a[0][j-1]==0)))
			{
				a[0][j]=0;
			}
			else if(j<m)
			{
				a[0][j]=1;
			}
			if((j<m)&&((x[j]!=y[0])&&(a[j-1][0]==0)))
			{
				a[j][0]=0;
			}
			else if(j<m)
			{
				a[j][0]=1;
			}
			for(int k=max(1, j-n+1); k<min(j, m); k++)
			{
				if(x[k]==y[j-k])
				{
					a[k][j-k]=a[k-1][j-k-1]+1;
				}
				else
				{
					a[k][j-k]=max(a[k-1][j-k], a[k][j-k-1]);
				}
			}
		}
		cout << a[m-1][n-1] << endl;
	}
	return 0;
}

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

#define MAX 150
#define MAXL 1000

int C[MAXL + 1][MAXL + 1];

int lec(string X, string Y)
{
	int XL = X.length();
	int YL = Y.length();
	X = ' ' + X;
	Y = ' ' + Y;
	for (int i = 0; i <=XL; i++)
		C[i][0] = 0;
	for (int i = 0; i <=YL; i++)
		C[0][i] = 0;
	for (int i = 1; i <=XL; i++)
	{
		for (int j = 1; j <=YL; j++)
		{
			if (X[i] == Y[j])
			{
				C[i][j] = C[i - 1][j - 1] + 1;
			}
			else if (C[i - 1][j] > C[i][j - 1])
			{
				C[i][j] = C[i - 1][j];
			}
			else{
				C[i][j] = C[i][j - 1];
			}
		}
	}
	return C[XL][YL];
}

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

C++: #include <iostream>
#include <string>
#include <algorithm>
    using namespace std;
int lcs(string x,string y){
    int c[1010][1010];
    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(){
    int q;
    string x;
    string y;
    scanf("%d",&q);
    for (int i=0; i<q; i++) {
        cin>>x>>y;
        cout<<lcs(x, y)<<endl;
    }
    return 0;
}