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 <bits/stdc++.h>
#include <tuple>

#define REP(i, n) for(int i=0;i<(int)(n);i++)
#define ALL(x) (x).begin(),(x).end()
const int INF = 1e9;

using namespace std;
int dp[1005][1005];

int main() {
    int n; cin >> n;
    REP(k, n){
        REP(i, 1005) REP(j, 1005) dp[i][j] = 0;
        string a, b;
        cin >> a >> b;
        REP(i, a.length()){
            string q = a.substr(i, 1);
            REP(j, b.length()){
                string t = b.substr(j, 1);
                if(q == t){
                    if(i == 0 || j == 0)
                        dp[i][j] = 1;
                    else
                        dp[i][j] = max(dp[i-1][j], dp[i][j-1] + 1);
                }
                if (i != 0 && j != 0)
                    dp[i][j] = (dp[i-1][j] > dp[i][j-1]) ? max(dp[i][j], dp[i-1][j]) : max(dp[i][j], dp[i][j-1]);
                else if (i != 0)
                    dp[i][j] = max(dp[i][j], dp[i-1][j]);
            }
        }
        cout << dp[a.length()-1][b.length()-1] << endl;
    }
    return 0;
}

C++: //	created : 16/03/15
// 	author   : Rp7rf
#include <iostream>
#include <vector>
#include <algorithm>
#include <cstdio>
#include <cstring>
#include <set>
typedef long long ll;
typedef unsigned long long ull;
using namespace std;
#define rep(i,a) for(int i = 0 ; i < a ; i ++)
#define loop(i,a,b) for(int i = a ; i < b ; i ++)
#define vi vector<int>
#define mp make_pair
#define pb push_back
#define MOD 1000000007
#define INF 1e9


int main(void){
	int n;
	string s1,s2;
	cin>>n;
	int dp[1000][1000];
	rep(i,n){
		int ret = 0;
		cin>>s1>>s2;
		rep(i,s1.size()+1)dp[i][0] = 0;
		rep(j,s2.size()+1)dp[0][j] = 0;

		loop(i,1,s1.size()+1){
			loop(j,1,s2.size()+1){
				if(s1[i] == s2[j]){
					dp[i][j] = dp[i-1][j-1] + 1;
				}else{
					dp[i][j] = max(dp[i-1][j],dp[i][j-1]);
				}
				ret = max(ret,dp[i][j]);
			}
		}
		cout<<ret<<endl;
	}
}

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();
  
  for (int i = 0; i < m; i++) c[i][0] = 0;
  for (int i = 0; i < n; i++) c[0][i] = 0;

  for (int i = 0; i < m; i++) {
    for (int j = 0; j < n; j++) {
      if (X[i] == Y[j]) 
        if (i == 0 || j == 0) 
          c[i][j] = 1;
        else 
          c[i][j] = c[i - 1][j - 1] + 1;
      else
        if (i != 0 && j != 0) 
          c[i][j] = max(c[i][j - 1], c[i - 1][j]);
    }
  }
  return c[m - 1][n - 1];
}

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++: #include <iostream>
#include <algorithm>
using namespace std;

static const int N = 100;

int main()
{
	int n, p[N + 1], m[N + 1][N + 1];
	cin >> n;
	for (int i = 1; i <= n; i++) cin >> p[i - 1] >> p[i];
	for (int i = 1; i <= n; i++) m[i][i] = 0;

	for (int l = 2; l <= n; l++)
	{
		for (int i = 1; i <= n; i++)
		{
			int j = i + l - 1;
			m[i][j] = 1 << 21;
			for (int k = i; k <= j - 1; k++)
			{
				m[i][j] = min(m[i][j], m[i][k] + m[k + 1][j] * p[i - 1] * p[k] * p[j]);
			}
		}
	}

	cout << m[1][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 = 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 = 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++: #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=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)<<endl;
  }
  return 0;
}

C++: #include <iostream>
#include <string>
#include <cstring>
#include <fstream>
#include <cmath>
#include <iomanip>
#include <cstdlib>
#include <algorithm>
#include <vector>
#include <map>
#include <deque>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <list>
#include <unordered_map>



using namespace std;

const int N = 10000;

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][j-1],c[i-1][j]);
            }
            maxl = max(maxl,c[i][j]);
        }
    }
    return maxl;
}

int main() {
    

    string s1,s2;
    int p;
    cin >> p;
    for (int i= 0;i<p;i++){
        cin >> s1 >> s2;
        cout << lcs(s1,s2) << endl;
    }
    return 0;


}

C++: #include<iostream>
#include<string>
#include<algorithm>
#include<vector>

using namespace std;

string s1, s2;

int lcs() {
  int i, j;
  int dp[s1.length()+1][s2.length()+1] = {};
  
  for(i = 1; i <= s1.length(); i++) {
    for(j = 1; j <= s2.length(); j++) {
      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]);
    }
  
  }
  return dp[s1.length()][s2.length()];
}

int main(){
  int n;
  cin >> n;
  while(n--) {
    cin >> s1 >> s2;
    cout << lcs() << endl;
  }
  
  return 0;
}