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 <iostream>
using namespace std;

int L[1010][1010]={};
string s,t;
int o,p;

int main(){
  int N;
  cin >> N;
  for(int n=0;n<N;n++){
    cin >> s >> t;
    o=s.size();
    p=t.size();
    for(int A=0;A<1010;A++){
      for(int B=0;B<1010;B++){
        L[A][B]=0;
      }
    }
    for(int i=1;i<=o;i++){
      for(int j=1;j<=p;j++){
        if(s[i-1]==t[j-1]){
          L[i][j]=1+L[i-1][j-1];
        }
        else
        L[i][j]=max(L[i][j-1],L[i-1][j]);
      }
    }
    cout << L[o][p] << endl;
  }
}

C++: ///
// File:  alds1_10_c.cpp
// Author: ymiyamoto
//
// Created on Tue Oct 17 01:36:16 2017
//

#include <cstdint>
#include <iostream>
#include <string>

using namespace std;
static uint32_t dp[1000][1000];

static void init_dp(uint32_t len1, uint32_t len2)
{
  for (uint32_t i = 0; i < len1; i++) {
    dp[i][0] = 0;
  }
  for (uint32_t i = 0; i < len2; i++) {
    dp[0][i] = 0;
  }
}

int32_t main()
{
  uint32_t n;
  cin >> n;

  for (uint32_t i = 0; i < n; i++) {
    string str1, str2;
    cin >> str1;
    cin >> str2;
    init_dp(str1.size(), str2.size());
    for (uint32_t i = 1; i <= str1.size(); i++) {
      for (uint32_t j = 1; j <= str2.size(); j++) {
        if (str1[i - 1] == str2[j - 1]) {
          dp[i][j] = dp[i - 1][j - 1] + 1;
        } else {
          dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]);
        }
      }
    }
    cout << dp[str1.size()][str2.size()] << endl;
  }

  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;
  int m = X.size();
  int n = Y.size();
  X = ' ' + X;
  Y = ' ' + Y;

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

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

  for (int i = 1; i <= m; i++) {
    for (int j = 1; j <= n; 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];

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

  return max;
}

int main(int argc, char const *argv[]) {
  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++: /**
 *    author  : 𝒌𝒚𝒐𝒎𝒖𝒌𝒚𝒐𝒎𝒖𝒑𝒖𝒓𝒊𝒏
 *    created : 2020-03-03 00:50:37
**/

#include <iostream>
#include <deque>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>
#include <algorithm>
#include <cmath>
#include <complex>
#include <numeric>
#include <bitset>
#include <cassert>
#include <cctype>
#include <iomanip>
#include <random>
#include <utility>
#include <chrono>

using namespace std;

using int64 = long long;

template<class T> using binary_heap = std::priority_queue<T, std::vector<T>, std::greater<T>>;
template<class T> std::ostream& operator<<(std::ostream& os, const std::vector<T>& vec) { os << '{'; size_t n = vec.size(); for (size_t i = 0; i < n; ++i) { os << vec[i]; if (i != n - 1) os << ','; } os << '}'; return os; }
template<class T, class U> std::ostream& operator<<(std::ostream& os, const std::pair<T, U>& p) { return os << '{' << p.first << " " << p.second << '}'; }
template<class T, class U> std::ostream& operator<<(std::ostream& os, const std::map<T, U>& mp) { os << '{'; for (auto it = mp.begin(); it != mp.end(); ++it) { os << '{' << it->first << ':' << it->second << '}'; if (it != --mp.end()) os << ','; } os << '}'; return os; }
template<class T> std::ostream& operator<<(std::ostream& os, const std::set<T>& st) { os << '{'; for (auto it = st.begin(); it != st.end(); ++it) { os << *it; if (it != --st.end()) os << ','; } os << '}'; return os; }
template<class T> std::istream& operator>>(std::istream& is, std::vector<T>& vec) { size_t n = vec.size(); for (size_t i = 0; i < n; ++i) is >> vec[i]; return is; }

#define all(_) begin(_), end(_)
#define rall(_) rbegin(_), rend(_)

#ifdef LOCAL
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]: ", debug_out(__VA_ARGS__)
#else
#define debug(...) 1728
#endif

void debug_out() { std::cerr << '\n'; }

template <class Head, class... Tail>
void debug_out(Head&& head, Tail&&... tail) {
  std::cerr << head;
  if (sizeof...(Tail) != 0) std::cerr << ", ";
  debug_out(std::forward<Tail>(tail)...);
}

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);

  int q; cin >> q;

  while (q--) {
    string s, t; cin >> s >> t;
    int n = s.size(), m = t.size();
    vector<vector<int>> dp(n + 1, vector<int>(m + 1, 0));
    dp[0][0] = 0;
    for (int i = 0; i < n; ++i) {
      for (int j = 0; j < m; ++j) {
        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[n][m] << '\n';
  };

  return 0;
}

C++: #include<iostream>
#include<algorithm>
#include<string>
#define MAX 1001
using namespace std;

string x, y;

int c[MAX][MAX];
int lcs(int m, int n);

int main() {
	int i, q, n, m;
	cin >> q;
	for (i = 0; i < q; i++) {
		cin >> x >> y;
		cout << lcs(x.length(), y.length()) << endl;
	}
	return 0;
}

int lcs(int m, int n) {
	int i, j, maxl = 0;
	c[0][0] = 0;
	for (i = 1; 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 - 1] == y[j - 1])c[i][j] = c[i - 1][j - 1] + 1;
			else c[i][j] = max(c[i][j - 1], c[i - 1][j]);
			maxl = max(maxl, c[i][j]);
		}
	}
	return maxl;
}