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 <vector>
#include <algorithm>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstring>
//#include <chrono> //1e+9で割る auto end= chrono::system_clock::now()-st;  cout<<end.count()%1e+9<<endl;
using namespace std;
typedef long long ll;
typedef pair<int,int> P;
typedef pair<ll,ll> LP;
typedef long double db;

#define fr first
#define sc second
#define pb push_back
#define rep(i,x) for(int i=0;i<x;i++)
#define rep1(i,x) for(int i=1;i<=x;i++)
#define rrep(i,x) for(int i=x-1;i>=0;i--)
#define rrep1(i,x) for(int i=x;i>0;i--)

int q;
string s1,s2;
int ans;
int dp[150][150];
int main()
{
	cin>>q;
	rep(i,q){
		cin>>s1>>s2;
		rep(i,s1.size()){
			rep(j,s2.size()){
				dp[i][j]=0;
			}
		}
		if(s1[0]==s2[0]) dp[0][0]=1;
		rep1(i,s1.size()-1){
			if(s1[i]==s2[0]) dp[i][0]=1;
			dp[i][0]=max(dp[i][0],dp[i-1][0]);
		}
		rep1(i,s2.size()-1){
			if(s1[0]==s2[i]) dp[0][i]=1;
			dp[0][i]=max(dp[0][i],dp[0][i-1]);
		}
		rep1(i,s1.size()-1){
			rep1(j,s2.size()-1){
				dp[i][j]=max( dp[i-1][j], dp[i][j-1] );
				if(s1[i]==s2[j]) dp[i][j]= max(dp[i][j],dp[i-1][j-1]+1);
			}
		}
		cout<<dp[s1.size()-1][s2.size()-1]<<endl;
	}
}

C++: //
//  main.cpp
//  longest_common_subsequence
//
//  Created by ???????????? on 2017/10/17.
//  Copyright ?? 2017 ????????????. All rights reserved.
//

#include <iostream>
#include <stdio.h>
#include <string.h>

using namespace std;

char X[1005];
char Y[1005];

void lcs(){
    size_t m = strlen(X);
    size_t n = strlen(Y);
    int c[m+1][n+1];
    c[0][0] = 0;
    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 if(c[i-1][j] >= c[i][j-1]){
                c[i][j] = c[i-1][j];
            }
            else{
                c[i][j] = c[i][j-1];
            }
        }
    }
    cout << c[m][n] << endl;
//    cout << c[m+1][n+1] << endl;
}

int main(int argc, const char * argv[]) {
    int n, i;
    scanf("%d", &n);
    for (i = 0; i < n; i++){
        scanf("%s", X);
        scanf("%s", Y);
        lcs();
    }
//    std::cout << "Hello, World!\n";
    return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
//BEGIN CUT HERE
int lcs(string X,string Y){
  const int N=max(X.size(),Y.size())+1;
  vector<vector<int> > c(N,vector<int>(N,0));
  int m = X.size();
  int n = Y.size();
  int maxl = 0;
  X = ' ' + X;
  Y = ' ' + Y;
  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;
}
//END CUT HERE
int main(){
  int q;
  cin>>q;
  while(q--){
    string s,t;
    cin>>s>>t;
    cout<<lcs(s,t)<<endl;
  }
  return 0;
}
/*
verified on 2017/06/29
http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=ALDS1_10_C
*/

C++: //INCLUDE
//------------------------------------------
#include <bits/stdc++.h>
//DEFINE
//------------------------------------------
#define ll long long
#define ld long double
#define ALLv(a)  (a).begin(),(a).end()
#define ALL(a,n)  (a),(a)+n
#define vi vector<long long>
#define vd vector<long double>
#define vs vector<string>
#define dcml(n) fixed<<setprecision(n)
//CONST
//------------------------------------------
const ll INF=1010000000000000017LL;
const ll MOD=1000000007LL;
const ld EPS=1e-12;
const ld PI=3.14159265358979323846;
//REPEAT
//------------------------------------------
#define   FOR(i,m,n) for(ll (i)=(m);   (i)<(n);  (i)++)
#define  FORS(i,m,n) for(ll (i)=(m);   (i)<=(n); (i)++)
#define  RFOR(i,m,n) for(ll (i)=(n)-1; (i)>=(n); (i)--)
#define RFORS(i,m,n) for(ll (i)=(n);   (i)>(n);  (i)--)
#define   REP(i,n)   for(ll (i)=0;     (i)<(n);  (i)++)
#define  REPS(i,x)   for(ll (i)=1;     (i)<=(x); (i)++)
#define  RREP(i,x)   for(ll (i)=(x)-1; (i)>=0;   (i)--)
#define RREPS(i,x)   for(ll (i)=(x);   (i)> 0;   (i)--)
#define  WREP(i,in,j,jn) REP(i,in)REP(j,jn)
#define WREPS(i,in,j,jn) REPS(i,in)REPS(j,jn)
//-----------------------------------------
//namespace
using namespace std;
//ライブラリはここに
//↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓

//-----------------------------------------
int main(void){
    ll Q;cin>>Q;
    REP(i,Q){
        string s1,s2;cin>>s1>>s2;
        ll n1=s1.size(),n2=s2.size();
        ll dp[n1+1][n2+1]={};
        REPS(i,n1){
            REPS(j,n2){
                if(s1[i-1]==s2[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[n1][n2]<<"\n";
    }
}

C++: n=int(input())
ans=[]
for k in range(n):
    s1=input()
    s2=input()
    dp=[[0 for i in range(len(s2)+1)] for j in range(len(s1)+1)]
    for i in range(1,len(s1)+1):
        for j in range(1,len(s2)+1):
            if s1[i-1]==s2[j-1]:
                dp[i][j]=dp[i-1][j-1]+1
            else:
                dp[i][j]=max(dp[i-1][j],dp[i][j-1])


    ans.append(dp[len(s1)][len(s2)])
for a in ans:
    print(a)