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 <iostream>
#include <string>
#include <algorithm>

using namespace std;

string str1,str2;

int m[1000][1000];

int LCS(int i,int j){
  
  if(m[i][j]!=0){
    return m[i][j];
  }
  if(i==-1||j==-1){
    return 0;
  }else if(str1[i]==str2[j]){
    m[i][j]=LCS(i-1,j-1)+1;
    return m[i][j];
  }else{
    m[i][j]=max(LCS(i-1,j),LCS(i,j-1));
    return m[i][j];
  }
  
}

int main(){
  int N;
  
  cin >> N;
  
  
  for(int i=0;i<N;i++){
    cin >> str1 >> str2;
    for(int j=0;j<1000;j++){
      for(int k=0;k<1000;k++){
        m[j][k]=0;
      }
    }
    cout << LCS(str1.size()-1,str2.size()-1) << endl;
  }
  return 0;
}

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

using namespace std;
typedef long long int ll;
typedef pair<int, int> P;
typedef pair<ll, ll> Pll;
typedef vector<int> Vi;
typedef tuple<int, int, int> T;
#define FOR(i,s,x) for(int i=s;i<(int)(x);i++)
#define REP(i,x) FOR(i,0,x)
#define ALL(c) c.begin(), c.end()
#define DUMP( x ) cerr << #x << " = " << ( x ) << endl

int dp[2][1024];

int main() {
  // use scanf in CodeForces!
  cin.tie(0);
  ios_base::sync_with_stdio(false);

  int N;
  cin >> N;
  REP(q, N) {
    memset(dp, 0, sizeof(dp));
    string X, Y;
    cin >> X >> Y;
    int LX = X.size(), LY = Y.size();
    REP(i, LX) REP(j, LY) {
      if (X[i] == Y[j]) {
	dp[(i+1)%2][j+1] = max(dp[i%2][j] + 1, max(dp[(i+1)%2][j], dp[i%2][j+1]));
      } else {
	dp[(i+1)%2][j+1] = max(dp[(i+1)%2][j], dp[i%2][j+1]);
      }
    }
    cout << dp[LX%2][LY] << endl;
  }
  return 0;
}

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

using namespace std;

#define 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++: #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++: //ALDS1_10C
#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
using namespace std;

static const int N=1001;

int lcs(string X,string Y){
 vector< vector<int> > c(N,vector<int>(N));
 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;
 }

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 <bits/stdc++.h>

using namespace std;

#define rep(i,x) for(int i=0;i<x;++i)
#define rrep(i,x) for(int i=x-1;i>=0;--i)

int dp[1010][1010];

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

    rep(_, q) {
        memset(dp, -1, sizeof(dp));
        dp[0][0] = 0;

        string a,b; cin >> a>>b;

        int n = a.size(), m = b.size();

        a += '$';
        b += '!';

        rep(i, n+1) {
            rep(j, m+1) {
                dp[i + 1][j] = max(dp[i + 1][j], dp[i][j]);
                dp[i][j + 1] = max(dp[i][j + 1], dp[i][j]);

                if (a[i] == b[j]) {
                    dp[i + 1][j + 1] = max(dp[i + 1][j + 1], dp[i][j] + 1);
                }
            }
        }

        cout << dp[n][m] << endl;
    }
}

C++: #define PI 3.14159265359
#define INF 2000000000
#define MAX 500000
#include <map>
#include <algorithm>
#include <vector>
#include <queue>
#include <iostream>
#include <string>
#include <cstring>
#include <cmath>
#include <cstdio>
using namespace std;
typedef long long ll;

void LCS(string X,string Y){
 int c[1000][1000];
 int n=X.length(),m=Y.length();
 for(int i=0;i<=max(n,m);i++){
     c[i][0]=c[0][i]=0;
 }
 for(int i=1;i<=n;i++){
     for(int j=1;j<=m;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]);
         }
     }
 }
 cout<<c[n][m]<<endl;
}

int main(){
    int q;
    cin>>q;
    string X,Y;
    for(int i=0;i<q;i++){
        cin>>X>>Y;
        LCS(X,Y);
    }
}

C++: #include<iostream>
#include<string>
#include<cstring>
#include<algorithm>
#define MAX_N 1000
int dp[MAX_N][MAX_N];
int solve(std::string s,std::string t){
        
        memset(dp,0,sizeof(dp));
        int n,m;
        n=s.size(),m=t.size();
        for(int i=0;i<n;i++){
                for(int j=0;j<m;j++){
                        if(s[i]==t[j])
                                dp[i+1][j+1]=dp[i][j]+1;
                        else
                                dp[i+1][j+1]=std::max(dp[i][j+1],dp[i+1][j\
]);
                }
        }
        return dp[n][m];
}

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