Go: package main

/*
最長共通部分列
*/

import (
	"bufio"
	"bytes"
	"fmt"
	"log"
	"os"
	"strconv"
	"strings"
)

func larger(l, r int) int {
	if l > r {
		return l
	}
	return r
}

var memo [1001][1001]int

func countLCS(x, y string) int {
	x = " " + x
	y = " " + y
	max := 0
	for xi := 1; xi < len(x); xi++ {
		for yi := 1; yi < len(y); yi++ {
			if x[xi] == y[yi] {
				memo[xi][yi] = memo[xi-1][yi-1] + 1
			} else {
				memo[xi][yi] = larger(memo[xi-1][yi], memo[xi][yi-1])
			}
			max = larger(max, memo[xi][yi])
		}
	}
	return max
}

func main() {
	scanner := makeScanner(1024)
	q := eGetInt(scanner)
	for i := 0; i < q; i++ {
		x := eGetLine(scanner)
		y := eGetLine(scanner)
		fmt.Println(countLCS(x, y))
	}
}

////////////////////////////////////////////////////////////////////////////////
// ライブラリ
////////////////////////////////////////////////////////////////////////////////
func makeScanner(maxByte int) *bufio.Scanner {
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Buffer(make([]uint8, 0, 8192), maxByte)
	return scanner
}
func makeWordScanner() *bufio.Scanner {
	scanner := makeScanner(8192)
	scanner.Split(bufio.ScanWords)
	return scanner
}
func eGetLine(r *bufio.Scanner) string {
	if r.Scan() {
		return r.Text()
	}
	err := r.Err()
	if err != nil {
		log.Fatal(err)
	}
	// EOF
	return ""
}
func eGetInt(r *bufio.Scanner) int {
	line := eGetLine(r)
	return eAtoi(line)
}
func eGetFields(r *bufio.Scanner) []string {
	line := eGetLine(r)
	return strings.Fields(line)
}
func eGetInts(r *bufio.Scanner) []int {
	fields := eGetFields(r)
	ints := make([]int, len(fields))
	for i := 0; i < len(ints); i++ {
		ints[i] = eAtoi(fields[i])
	}
	return ints
}
func eGetChars(r *bufio.Scanner) []string {
	line := eGetLine(r)
	return strings.Split(line, "")
}
func eAtoi(s string) int {
	n, err := strconv.Atoi(s)
	if err != nil {
		log.Fatal(err)
	}
	return n
}

type ints []int

func (s ints) String() string {
	var buf bytes.Buffer
	buf.WriteString("[")
	sep := ""
	for _, v := range s {
		buf.WriteString(fmt.Sprintf("%s%d", sep, v))
		sep = ", "
	}
	buf.WriteString("]")
	return buf.String()
}

func reverse(a ints) ints {
	r := make(ints, len(a))
	for i := 0; i < len(a); i++ {
		r[i] = a[len(a)-1-i]
	}
	return r
}
func max(a ints) (int, bool) {
	if len(a) == 0 {
		return 0, false
	}
	m := a[0]
	for _, e := range a {
		if e > m {
			m = e
		}
	}
	return m, true
}
func min(a []int) int {
	m := a[0]
	for _, v := range a {
		if v < m {
			m = v
		}
	}
	return m
}

func sum(a ints) int {
	if len(a) == 0 {
		return 0
	}
	sum := 0
	for _, e := range a {
		sum += e
	}
	return sum
}
func find(n int, a ints) int {
	for i, v := range a {
		if n == v {
			return i
		}
	}
	return -1
}

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

#define M_PI       3.14159265358979323846   // pi

using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef vector<ll> VI;
typedef pair<ll, ll> P;
typedef tuple<ll, ll, ll> t3;
typedef tuple<ll, ll, ll, ll> t4;
typedef tuple<ll, ll, ll, ll, ll> t5;

#define rep(a,n) for(ll a = 0;a < n;a++)
#define repi(a,b,n) for(ll a = b;a < n;a++)

using namespace std;

static const ll INF = 1e15;

struct LongestCommonSubsequence {
    static const int max_length = 1001;
    std::vector<std::vector<int>> dp;
    std::vector<std::vector<int>> pre;
    std::string s, t;

    LongestCommonSubsequence(std::string left, std::string right) {
        s = "+" + left;
        t = "*" + right;
        dp.assign(max_length, std::vector<int>(max_length, 0));
        pre.assign(max_length, std::vector<int>(max_length, 0));
    }

    void lcs() {

        for (int si = 1; si < s.size(); si++) {
            for (int ti = 1; ti < t.size(); ti++) {
                if (s[si] == t[ti]) {
                    dp[si][ti] = dp[si - 1][ti - 1] + 1;
                    pre[si][ti] = 1;
                }
                else if (dp[si - 1][ti] > dp[si][ti - 1]) {
                    dp[si][ti] = dp[si - 1][ti];
                    pre[si][ti] = 2;
                }
                else {
                    dp[si][ti] = dp[si][ti - 1];
                    pre[si][ti] = 3;
                }
            }
        }
    }

    std::string solve() {
        std::string ans = "";

        int si = s.size() - 1;
        int ti = t.size() - 1;
        while (si >= 1 && ti >= 1) {
            if (pre[si][ti] == 1) {
                ans += s[si];
                si--, ti--;
            }
            else if (pre[si][ti] == 2) {
                si--;
            }
            else {
                ti--;
            }
        }

        reverse(ans.begin(), ans.end());
        return ans;
    }
};

int main() {
    ll q;
    cin >> q;
    rep(i, q) {
        string s, t;
        cin >> s >> t;
        LongestCommonSubsequence seq(s, t);
        seq.lcs();
        cout << seq.solve().size() << endl;
    }
    return 0;
}

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

int main(){

  int n;
  int dp[1111][1111];

  cin >> n;
  while(n--){
    string str1, str2;
    cin >> str1 >> str2;

    memset(dp,0,sizeof(dp));

    for(int i = 1; i <= str1.size(); i++){
      for(int 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;

  }
}

C++: #include <algorithm>
#include <cassert>
#include <climits>
#include <cmath>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <string>
#include <vector>

using namespace std;
typedef long long ll;

int dp[1001][1001];

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int q;
  cin >> q;
  vector<string> xs(q), ys(q);
  for (int i = 0; i < q; i++) {
    cin >> xs[i] >> ys[i];
  }

  for (int i = 0; i < q; i++) {
    fill(dp[0], dp[1001], 0);
    string x = xs[i], y = ys[i];
    for (int j = 0; j < x.size(); j++) {
      for (int k = 0; k < y.size(); k++) {
        if (x[j] == y[k]) {
          dp[j + 1][k + 1] = dp[j][k] + 1;
        } else {
          dp[j + 1][k + 1] = max(dp[j][k + 1], dp[j + 1][k]);
        }
      }
    }

    cout << dp[x.size()][y.size()] << endl;
    ;
  }
  return 0;
}

C++: #include <algorithm>
#include <iostream>
#include <string>
#include <vector>
#include <utility>
#include <queue>
#include <cmath>
#include <set>
#include <iomanip>

using namespace std;

typedef long long ll;

int get_LCS(string x, string y){
  int nx = x.size(), ny = y.size();
  int dp[nx+1][ny+1];
  for(int i=0;i<=ny;i++) dp[0][i] = 0;
  for(int i=0;i<=nx;i++) dp[i][0] = 0;
  for(int i=1;i<=nx;i++){
    for(int j=1;j<=ny;j++){
      if(x[i] == y[j]) dp[i][j] = dp[i-1][j-1] + 1;
      else dp[i][j] = max(dp[i][j-1], dp[i-1][j]);
    }
  }
  return dp[nx][ny];
}

int main(){
  cin.tie(0);
  ios_base::sync_with_stdio(false);
  int q; cin >> q;
  for(int i=0;i<q;i++){
    string x, y; cin >> x >> y;
    cout << get_LCS(x, y) << endl;
  }
}

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

int lcs(string s1,string s2)
{
	int m = s1.size();
	int n = s2.size();
	int c[1005][1005];
	for (int i = 1; i <= m; i++)c[i][0] = 0;
	for (int j = 1; j <= n; j++)c[0][j] = 0;
	int maxz = 0;
	s1 = " " + s1;
	s2 = " " + s2;
	for(int i=1;i<=m;i++)
		for (int j = 1; j <= n; j++) {
			if (s1[i] == s2[j])
				c[i][j] = c[i-1][j-1] + 1;
			else {
				c[i][j] = max(c[i - 1][j], c[i][j - 1]);
			}
			maxz = max(maxz, c[i][j]);
		}
	return maxz;
}
int main()
{
	int N;
	scanf("%d", &N);
	while (N--) {
		string s1, s2;
		cin >> s1>>s2;
		cout << lcs(s1, s2) << endl;
	}
	return 0;
}