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++: #pragma region Macros
#include <bits/stdc++.h>

#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define REP(i, n) FOR(i, 0, n)
#define ALL(a) (a).begin(), (a).end()
#define SZ(x) ((int)(x).size())
#define IN(x, a, b) x >= a and x < b

using namespace std;
using ll = long long;

template <class T> bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T> bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return 1;
  }
  return 0;
}
template <typename T> constexpr T INF = numeric_limits<T>::max() / 2;
#pragma endregion

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

  int n;
  cin >> n;
  REP(_, n) {
    string a, b;
    cin >> a >> b;
    vector<vector<int>> dp(a.size() + 1, vector<int>(b.size() + 1, 0));
    REP(i, a.size()) {
      REP(j, b.size()) {
        if (a[i] == b[j]) {
          dp[i + 1][j + 1] = dp[i][j] + 1;
        }
        chmax(dp[i + 1][j + 1], dp[i][j + 1]);
        chmax(dp[i + 1][j + 1], dp[i + 1][j]);
      }
    }
    cout << dp[a.size()][b.size()] << endl;
  }

  return 0;
}

C++: #include<iostream>

using namespace std;

int q;

string x, y;

int dp(string x, string y){
  int longest[1051][1051];
  for(int j = 1; j <= y.size(); ++j){
    for(int i = 1; i <= x.size(); ++i){
      if(i <= 0 || j <= 0){
        longest[i][j] = 0;
      }else if(x[i - 1] == y[j - 1]){
        longest[i][j] = 1 + longest[i-1][j-1];
      }else{
        longest[i][j] = max(longest[i][j -1], longest[i - 1][j]);
      }
    }
  }
  //cout << x.size() << endl;
  return longest[x.size()][y.size()];
}

int main(){
  cin >> q;
  while(q != 0){
    q--;
    cin >> x;
    cin >> y;
    
    cout << dp(x, y) << endl;
  }
}

C++: #include<bits/stdc++.h>
using namespace std;
int N=1000;
int lcs(string x,string  y){
    int c[N+1][N+1];
    int m=x.size();
    int n=y.size();
    int maxl=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]);
            }
            maxl=max(maxl,c[i][j]);
        }
    }
    return maxl;
}
int main(){
    string  s1,s2;
    int n; cin>>n;
    for(int i=0;i<n;i++){
        cin>>s1>>s2;
        cout<<lcs(s1,s2)<<'\n';
    }
    return 0;
}

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

typedef long long ll;
#define inf 1e9+7

int dp[1001][1001];
char x[1001],y[1001];

void init(){
    for(int i=0;i<1001;i++){
        dp[0][i]=0;
        dp[i][0]=0;
    }
}

void solve(int sn, int tn){
    for(int i=1;i<=sn;i++){
        for(int j=1;j<=tn;j++){
            if(x[i-1]==y[j-1])dp[i][j]=dp[i-1][j-1]+1;
            else dp[i][j]=max(dp[i-1][j], dp[i][j-1]);
        }
    }
}

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

    int n;
    cin >> n;
    string s,t;
    for(int i=0;i<n;i++){
        init();
        cin >> s >> t;
        int sn=s.size();
        int tn=t.size();
        for(int j=0;j<sn;j++){
            x[j]=s[j];
        }
        for(int j=0;j<tn;j++){
            y[j]=t[j];
        }

        solve(sn, tn);
        cout << dp[sn][tn] << endl;
    }

}

C++: #include <iostream>
#include <algorithm>
#include <stack>
#include <string>
#include <queue>
#include <cstdlib>
#include <cstdio>
#include <cmath>
#include <vector>
#include <list>
#include <string.h>
#define _USE_MATH_DEFINES
#include <math.h>
#include <map>
#define INFTY (1<<30)
#define MAX 100000000

using namespace std;

int lcs(string x, string y) {
	int m = x.size(), n = y.size();
	int c[1000+1][1000+1];
	x = ' ' + x; y = ' ' + y;
	for( int i = 0; i <= m; i++) c[i][0] = 0;
	for( int j = 0; j <= n; j++) c[0][j] = 0;
	for( int i = 1; i <= m; i++) {
		for( int j = 0; j <= n; j++) {
			if(x[i] == y[j]) c[i][j] = c[i-1][j-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[m][n];
}

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

	return 0;
}