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 <iostream>
#include <string>

using namespace std;

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

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<string>

#define PB push_back
#define ALL(a)  (a).begin(),(a).end()
#define DWN(a)  (a).begin(),(a).end(), greater<int>()
#define rep(i, m) for (int i = 0; i < m; i++)
#define REP(i, n, m) for (int i = n; i < m; i++)

#define mod 1000000007

using namespace std;

int q;
string s, t;
int dp[151][151];

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	cin >> q;
	rep(k, q) {
		cin >> s >> t;
		rep(i, q) rep(j, q) dp[i][j] = 0;
		rep(i, s.size()) {
			rep(j, t.size()) {
				if (s[i] == t[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[s.size()][t.size()] << "\n";
	}
	return 0;
}

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

int main()
{
	int q, t1, t2;
	string s1, s2;
	const int maxS = 1000;
	int m[maxS][maxS];

	cin >> q;

	for (int i = 0; i < q; i++) {

		for (int i = 0; i < maxS; i++)
			for (int j = 0; j < maxS; j++)
				m[i][j] = 0;

		cin >> s1 >> s2;

		t1 = s1.size() - 1;
		t2 = s2.size() - 1;

		if (s1[0] == s2[0])
			m[0][0] = 1;

		for (int i = 0; i < t1; i++) {
			int f = 0;
			if (s1[i + 1] == s2[0])
				f = 1;
			m[i + 1][0] = max(m[i][0], f);
		}

		for (int j = 0; j < t2; j++) {
			int f = 0;
			if (s2[j + 1] == s1[0])
				f = 1;
			m[0][j + 1] = max(m[0][j], f);
		}

		for (int i = 0; i < t1; i++) {
			for (int j = 0; j < t2; j++) {
				if (s1[i + 1] == s2[j + 1])
					m[i + 1][j + 1] = m[i][j] + 1;
				else
					m[i + 1][j + 1] = max(m[i][j + 1], m[i + 1][j]);
			}
		}

		cout << m[t1][t2] << 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 max1=0;
	x=" "+x;
	y=" "+y;
	for(int i=0;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]);
			}
			max1=max(max1,c[i][j]);
		}
	}
	return max1;
}
int main(){
	string s1,s2;
	int n;
	std::cin>>n;
	for(int i=0;i<n;i++){
		std::cin>>s1>>s2;
		std::cout<<lcs(s1,s2)<<"\n";
	}
	return 0;
}

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

int lcs(string str1, string str2)
{
  int m = str1.size(), n = str2.size();
  int c[1001][1001];
  str1 = ' ' + str1;
  str2 = ' ' + str2;
  for (int i = 1; i <= m; i++) c[i][0] = 0;
  for (int i = 1; i <= n; i++) c[0][i] = 0;

  for (int i = 1; i <= m; i++){
    for (int j = 1; j <= n; j++){
      if (str1[i] == str2[j]) c[i][j] = c[i - 1][j - 1] + 1;
      else c[i][j] = max(c[i - 1][j], c[i][j - 1]);
    }
  }
  return (c[m][n]);
}
int main()
{
  int q;
  cin >> q;
  while (q--){
    string str1, str2;
    cin >> str1 >> str2;
    cout << lcs(str1, str2) << endl;
  }
}

C++: #include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define MM 1000000000
#define MOD MM+7
#define MAX 301000
#define MAP 110
#define initial_value -1
#define Pair pair<int,int>
#define chmax(a,b) (a<b ? a=b:0)
#define chmin(a,b) (a>b ? a=b:0)
ll INF = 1e18;
int dx[4] = {-1,0,1,0};
int dy[4] = {0,-1,0,1};
//union_find
int par[100];
int depth[100];
ll N;
ll x[20],c[20],v[20];
string s,t;

int lcs(string x, string y){
    int dp[1010][1010];
    int m = x.size();
    int n = y.size();
    int mx = 0;
    x = ' ' + x;
    y = ' ' + y;
    for(int i = 0; i <= m; i++){
        for(int j = 0; j <= n; j++){
            dp[i][j] = 0;
        }
    }
    for(int i = 1; i <= m; i++){
        for(int j = 1; j <= n; j++){
            if(x[i] == y[i]){
                dp[i][j] = dp[i-1][j-1] + 1;
            } else {
                dp[i][j] = max(dp[i-1][j], dp[i][j-1]);
            }
            mx = max(mx, dp[i][j]);
        }
    }
    return mx;
}
int main(){
    cin >> N;
    for(int i = 0; i < N; i++){
        cin >> s >> t;
        cout << lcs(s,t) << endl;
    }
}

C++: #include <cstdio>
#include <iostream>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <string>
#include <vector>
#include <list>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <bitset>
#include <numeric>
#include <climits>
#include <cfloat>
#include <functional>
#include <cctype>

using namespace std;

#define REP(i,n) for(int i = 0; i < (int)n; ++i)

string X, Y;

void solve(int x_size, int y_size)
{
	vector< vector<int> > dp(x_size + 1, vector<int>(y_size + 1));

	for(int i = 0; i < x_size; ++i) {
		for(int j = 0; j < y_size; ++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]);
			}
		}
	}

	cout << dp[X.size()][Y.size()] << endl;
}

int main()
{
	std::ios::sync_with_stdio(false);
	std::cin.tie(0);

	int n;
	cin >> n;
	REP(i, n) {
		cin >> X >> Y;
		solve(X.size(), Y.size());
	}
	return 0;
}