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 <string>
using namespace std;

int main(void){
    int L[1010][1010], Z;
    string X, Y;
    int q;
    
    cin >> q;
    for(int k=0; k<q; k++){
        cin >> X;
        cin >> Y;
    for(int i=0; i<X.size(); i++){
        for(int j=0; j<Y.size(); j++){
            L[i][j] = 0;
        }
    }
    
    for(int i=0; i<X.size(); i++){
        for(int j=0; j<Y.size(); j++){
            if(i<=0 || j<=0){
                if(X[i]==Y[j])  L[i][j]=1;
                else            L[i][j]=0;
            }
            else if(X[i] == Y[j])    L[i][j]=1+L[i-1][j-1];
            else L[i][j]=max(L[i][j-1], L[i-1][j]);
            Z=L[i][j];
        }
    }
    
    cout << Z << endl;
    
    }
    return 0;
}

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

const int MAX = 1000;
static int n, m;
static char S[150][MAX], T[150][MAX];
static int ans[150][MAX];
void solve(int in)
{
	int count_max = 0;
	for (int i = n - 1; i >= 0; i--) {
		count_max = 0;
		for (int j = n - 1; j >= 0; j--) {
			int count = 0;
			int tem_i = i, tem_j = j;
			//?????´??????????????????????????????????????´????????´????????¢?´¢??????
			if (S[in][tem_i] == T[in][tem_j] && S[in][tem_i + 1] == T[in][tem_j + 1] && tem_i + 1 < n && tem_j + 1 < m)
				break;
			while (S[in][tem_i] == T[in][tem_j]&& tem_i>=0 && tem_j>=0 ) {
				count++;
				tem_i--;
				tem_j--;
			}
			if (count_max < count) {
				count_max = count;
			}
		}
		ans[in][i] = count_max;
		//???????????§??§i??????????????§?????¨??????????±???????.
	}
}
int main()
{
	int q;
	cin >> q;
	for (int i = 0; i < q; i++) {
		cin >> S[i];
		cin >> T[i];
		n = (int)strlen(S[i]);
		m = (int)strlen(T[i]);
		solve(i);
	}

	for (int i = 0; i < q; i++)
	cout << *max_element(&ans[i][0], &ans[i][n]) << 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 maxl = 0;
  X = ' ' + X;
  Y = ' ' + Y;
  for(int i = 1; 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) << endl;
  }
  return 0;
}

C++: //http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=ALDS1_10_C&lang=ja
// Longest Common Subsequence
// LCS
//http://nocotan.github.io/%E3%82%A2%E3%83%AB%E3%82%B4%E3%83%AA%E3%82%BA%E3%83%A0/2017/01/23/lcs-copy.html
#include <bits/stdc++.h>
#if LOCAL
#include "dump.hpp"
#else
#define dump(...)
#endif
using namespace std;
using ll=long long;
#define FOR(i,a,b) for(ll i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)
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;}
void solve(){
    string X,Y; cin>>X>>Y;
    vector<vector<ll>> dp(X.size()+1,vector<ll>(Y.size()+1));
    //
    FOR(i,0,X.size()){
        FOR(j,0,Y.size()){
            if(X[i]==Y[j]) chmax(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[X.size()][Y.size()]<<endl;
}
int main() {
    ll q; cin>>q;    
    REP(i,q){
        solve();
    }
    return 0;
}

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

using namespace std;

int solve(string &s, string &t, vector<vector<int>> &memo, int i = 0,
          int j = 0) {
  if (i >= s.size() || j >= t.size()) {
    return 0;
  }

  if (memo[i][j] < 0) {
    if (*(s.end() - i - 1) == *(t.end() - j - 1)) {
      memo[i][j] = solve(s, t, memo, i + 1, j + 1) + 1;
    } else {
      memo[i][j] =
          max(solve(s, t, memo, i + 1, j), solve(s, t, memo, i, j + 1));
    }
  }

  return memo[i][j];
}
int main(int argc, char *argv[]) {
  int n;
  cin >> n;
  for (int i = 0; i < n; ++i) {
    string s, t;
    cin >> s >> t;
    vector<vector<int>> memo(s.size(), vector<int>(t.size(), -1));
    cout << solve(s, t, memo) << '\n';
  }

  return 0;
}

C++: #include<cstdio>
#include<cstring>
#include<algorithm>

using namespace std;

int map[2000][2000];

int main(void) {
    int q;
    scanf("%d",&q);
    for(int i=0; i<q; i++) {
        char x[2000], y[2000];
        scanf("%s%s",x,y);
        int xl=strlen(x),yl=strlen(y);

        for(int m=0; m<xl; m++)
            map[m][0] = 0;
        for(int n=0; n<yl; n++)
            map[0][n] = 0;
        for(int m=1; m<=xl; m++)
            for(int n=1; n<=yl; n++) {
                if(x[m] == y[n])
                    map[m][n] = max(max(map[m-1][n-1]+1, map[m-1][n]), map[m][n-1]);
                else
                    map[m][n] = max(max(map[m-1][n-1]+0, map[m-1][n]), map[m][n-1]);
            }
        printf("%d\n", map[xl][yl]);
    }
    return 0;
}