Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

func getScanner(fp *os.File) *bufio.Scanner {
	scanner := bufio.NewScanner(fp)
	scanner.Split(bufio.ScanWords)
	scanner.Buffer(make([]byte, 500001), 500000)
	return scanner
}

func getNextString(scanner *bufio.Scanner) string {
	scanner.Scan()
	return scanner.Text()
}

func getNextInt(scanner *bufio.Scanner) int {
	i, _ := strconv.Atoi(getNextString(scanner))
	return i
}

func main() {
	fp := os.Stdin
	if len(os.Args) > 1 {
		fp, _ = os.Open(os.Args[1])
	}

	scanner := getScanner(fp)
	writer := bufio.NewWriter(os.Stdout)

	n := getNextInt(scanner)
	for i := 0; i < n; i++ {
		x := getNextString(scanner)
		y := getNextString(scanner)

		fmt.Fprintln(writer, lcs(x, y))
	}

	writer.Flush()
}

func lcs(x, y string) int {
	lx := len(x)
	ly := len(y)
	dp := make([][]int, lx+1)
	for i := 0; i <= lx; i++ {
		dp[i] = make([]int, ly+1)
	}
	for i := 0; i < lx; i++ {
		for ii := 0; ii < ly; ii++ {
			if x[i] == y[ii] {
				dp[i+1][ii+1] = dp[i][ii] + 1
				continue
			}
			dp[i+1][ii+1] = dp[i][ii+1]
			if dp[i+1][ii] > dp[i+1][ii+1] {
				dp[i+1][ii+1] = dp[i+1][ii]
			}
		}
	}
	return dp[lx][ly]
}

C++: //include
//------------------------------------------
#include <vector>
#include <list>
#include <map>
#include <set>
#include <deque>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <ctime>

using namespace std;

//------------------------------------------
inline int toInt(string s) {
    int v;
    istringstream sin(s);
    sin >> v;
    return v;
}

template<class T>
inline string toString(T x) {
    ostringstream sout;
    sout << x;
    return sout.str();
}

//------------------------------------------
template<class T>
inline T sqr(T x) { return x * x; }

//typedef
//------------------------------------------
typedef pair<int, int> PII;
typedef long long LL;
typedef vector<int> VI;
typedef vector<bool> VB;
typedef vector<VI> VVI;
typedef vector<VB> VVB;
typedef vector<string> VS;
typedef vector<LL> VLL;
typedef vector<VLL> VVLL;

//container util
//------------------------------------------
#define ALL(a)  (a).begin(),(a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define PB push_back
#define MP make_pair
#define SZ(a) int((a).size())
#define EACH(i, c) for(typeof((c).begin()) i=(c).begin(); i!=(c).end(); ++i)
#define EXIST(s, e) ((s).find(e)!=(s).end())
#define SORT(c) sort((c).begin(),(c).end())
#define RSORT(c) sort((c).rbegin(),(c).rend())

//repetition
//------------------------------------------
#define FOR(i, a, b) for(int i=(a);i<(b);++i)
#define REP(i, n)  FOR(i,0,n)
#define REPR(i, n) for(int i = n;i >= 0;i--)

//constant
//--------------------------------------------
const double EPS = 1e-10;
const double PI = acos(-1.0);
const int INF = 1 << 30;

//partial_permutation nPr
//first・・最初の数
//middle・・r(取り出す数)
//last・・n(全体数)
template<class BidirectionalIterator>
bool next_partial_permutation(BidirectionalIterator first, BidirectionalIterator middle, BidirectionalIterator last) {
    reverse(middle, last);
    return next_permutation(first, last);
}

//combination nCr
//first1・・最初の数
//last1==first2・・r(取り出す数)
//last2・・n(全体数)
template<class BidirectionalIterator>
bool next_combination(BidirectionalIterator first1, BidirectionalIterator last1, BidirectionalIterator first2,
                      BidirectionalIterator last2) {
    if ((first1 == last1) || (first2 == last2)) {
        return false;
    }
    BidirectionalIterator m1 = last1;
    BidirectionalIterator m2 = last2;
    --m2;
    while (--m1 != first1 && !(*m1 < *m2)) {
    }
    bool result = (m1 == first1) && !(*first1 < *m2);
    if (!result) {
        while (first2 != m2 && !(*m1 < *first2)) {
            ++first2;
        }
        first1 = m1;
        std::iter_swap(first1, first2);
        ++first1;
        ++first2;
    }
    if ((first1 != last1) && (first2 != last2)) {
        m1 = last1;
        m2 = first2;
        while ((m1 != first1) && (m2 != last2)) {
            std::iter_swap(--m1, m2);
            ++m2;
        }
        std::reverse(first1, m1);
        std::reverse(first1, last1);
        std::reverse(m2, last2);
        std::reverse(first2, last2);
    }
    return !result;
}

//clear memory
#define CLR(a, b) memset((a), (b),sizeof(a))

//debug
#define dump(x)  cerr << #x << " = " << (x) << endl;
#define debug(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << endl;



int main() {

    int q;
    cin >> q;

    REP(i, q){
        string X;
        string Y;
        cin >> X;
        cin >> Y;

        VVI dp;
        dp.resize(X.size()+1);
        REP(i, X.size()+1){
            dp[i].resize(Y.size()+1);
        }

        for(int i = 1; i<=X.size();i++){
            for(int j=1;j<=Y.size();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]);
                }
            }
        }

        cout<<dp[X.size()][Y.size()] << endl;

    }


    return 0;
}

C++: #include <iostream>
#include <string>
#include <cstdio>

using namespace std;

int minSequenceSize(string x, string y)
{
    int x_len = x.size();
    int y_len = y.size();
    int map[x_len][y_len] = {};

    for (int i = 0; i < x_len; i++)
    {
        for (int j = 0; j < y_len; j++)
        {
            if (i == 0)
            {
                map[0][j] = 0;
                continue;
            }
            if (j == 0)
            {
                map[i][0] = 0;
                continue;
            }

            if (x[i] == y[j])
            {
                map[i][j] = map[i - 1][j - 1] + 1;
                continue;
            }

            if (x[i] != y[j])
            {
                map[i][j] = max(map[i - 1][j], map[i][j - 1]);
                continue;
            }
        }
    }
    return map[x_len - 1][y_len - 1];
}

int main()
{
    int q;
    cin >> q;

    for (int i = 0; i < q; i++)
    {
        string x, y;
        cin >> x >> y;

        x = " " + x;
        y = " " + y;
        int ans = minSequenceSize(x, y);
        cout << ans << endl;
    }
}

C++: #include<iostream>
#include<algorithm>
#include<cstdio>
#include<string>
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 ;
}