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 <iostream>
#include <stdlib.h>
#include <algorithm>
using namespace std;

int LCS(string s, string t);

int main(void){
  int n;
  string s;
  string t;
  cin>>n;
  for(int i=0;i<n;i++){
    cin>>s;
    cin>>t;
    cout<<LCS(s,t)<<endl;
  }
}

int LCS(string s, string t){
  int a[s.length()+1][t.length()+1];
  for(int i=0;i<s.length()+1;i++){
    for(int j=0;j<t.length()+1;j++){
      a[i][j]=0;
    }
  }
  char S,T;
  for(int i=1;i<s.length()+1;i++){
    for(int j=1;j<t.length()+1;j++){
      S=s[i-1];
      T=t[j-1];
      if(S!=T){
        a[i][j]=max({a[i-1][j-1],a[i-1][j],a[i][j-1]});
      }
      else{
        a[i][j]=max({a[i-1][j-1]+1,a[i-1][j],a[i][j-1]});
      }
    }
  }
  return a[s.length()][t.length()];
}

C++: #include <bits/stdc++.h>
using ll = long long;
using namespace std;
#define rep(i,n) for(int i=0, i##_len=(int)(n); i<i##_len; i++)
#define reps(i,n) for(int i=1 , i##_len=(int)(n);i<=i##_len;i++)
#define rrep(i,n) for(int i=((int)(n)-1);i>=0;i--)
#define rreps(i,n) for(int i=((int)(n));i>0;i--)
#define all(x) (x).begin(), (x).end()
#define F first
#define S second
#define mp make_pair
#define pb push_back
#define solve(a) ((a)?"Yes":"No")
typedef vector<long long> V;
typedef vector<V> VV;
typedef pair<long long , long long> P;
typedef vector<P> VP;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1;} return 0;}
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1;} return 0;}
const long long INFLL = 1LL<<62;
const int INF = 1<<30;
const double PI=acos(-1);
int main(){
    int n;
    cin >>n;
    int a=0,b=0;
    string x,y;
    vector<vector<int>>dp(1010,vector<int>(1010,0));
    rep(_,n){
        rep(i,a+1){
            rep(j,b+1){
                dp[i][j]=0;
            }

        }
        cin>>x>>y;
        a=x.size();
        b=y.size();
       
        rep(i,a){
            rep(j,b){
                
                    chmax(dp[i+1][j+1],dp[i][j+1]);
                
                if(j!=0){
                    chmax(dp[i+1][j+1],dp[i+1][j]);
                }
                if(x[i]==y[j]){
                    chmax(dp[i+1][j+1],dp[i][j]+1);
                }
            }
        }
        cout<<dp[a][b]<<endl;
    }
    
}

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

const int MAX_N=1e3+5;

string s1,s2;

int dp[MAX_N][MAX_N];


int lcs(int i,int j){
	if(i==s1.size() || j==s2.size())return 0;
	if(dp[i][j]!=-1)return dp[i][j];
	if(s1[i]==s2[j])return dp[i][j]=lcs(i+1,j+1)+1;
	return dp[i][j]=max(lcs(i+1,j),lcs(i,j+1));
}

int main(){
	int n;
	cin>>n;
	for(int i=0;i<n;i++){
		s1.clear();s2.clear();
		for(int j=0;j<MAX_N;j++)fill(dp[j],dp[j]+MAX_N,-1);
		cin>>s1>>s2;
		cout<<lcs(0,0)<<endl;
	}
}

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];

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

  return max;
}

int main() {
  int N = 0;
  cin >> N;

  string X, Y;
  for (int i = 0; i < N; i++) {
    cin >> X >> Y;

    cout << lcs(X, Y) << endl;
  }

  return 0;
}

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

int longestCommonSubsequence(string X, string Y) {
	int DP_memory[1000+1][1000+1]; //0~length??????

	for (unsigned int i = 0; i <= X.length(); i++)
		DP_memory[i][0] = 0;
	for (unsigned int i = 0; i <= Y.length(); i++)
		DP_memory[0][i] = 0;

	for (unsigned int i = 1; i <= X.length(); i++) {
		for (unsigned int j = 1; j <= Y.length(); j++) {
			if (X[i] == Y[j])
				DP_memory[i][j] = DP_memory[i - 1][j - 1] + 1;
			else if (DP_memory[i - 1][j] >= DP_memory[i][j - 1])
				DP_memory[i][j] = DP_memory[i - 1][j];
			else
				DP_memory[i][j] = DP_memory[i][j - 1];
		}
	}
	return DP_memory[X.length()][Y.length()];
}

int main() {
	string lcsX[1000];
	string lcsY[1000];
	int setNum;

	cin >> setNum;
	for (int i = 0; i < setNum; i++) {
		cin >> lcsX[i];
		cin >> lcsY[i];

		int lcs = longestCommonSubsequence(lcsX[i], lcsY[i]);
		cout << lcs << endl;
	}
	return 0;
}

C++: #include <iostream>

using namespace std;

int lcs(string X, string Y) {
  int memo[1010][1010];
  int m = X.size();
  int n = Y.size();
  X = ' ' + X;
  Y = ' ' + Y;
  for (int i = 0; i < m; i++) {
    memo[i][0] = 0;
  }
  for (int j = 0; j < m; j++) {
    memo[0][j] = 0;
  }
  int max_lcs = 0;
  for (int i = 1; i <= m; i++) {
    for (int j = 1; j <= n; j++) {
      if (X[i] == Y[j]) {
        memo[i][j] = memo[i-1][j-1] + 1;
      } else {
        memo[i][j] = max(memo[i][j-1], memo[i-1][j]);
      }
      max_lcs = max(max_lcs, memo[i][j]);
    }
  }
  return max_lcs;
}

int main() {
  int q;
  cin >> q;
  for (int i = 0; i < q; i++) {
    string X, Y;
    cin >> X >> Y;
    cout << lcs(X, Y) << endl;
  }
}