Go: package main

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

// define
var (
	sc = bufio.NewScanner(os.Stdin)
)

func bordersInt(in_map [][]int, invalid int) [][]int{
	H, W := len(in_map), len(in_map[0])
	out_map := make([][]int, H+2)
	for h:=0; h<H+2; h++ {
		out_map[h] = make([]int, W+2)
		for w:=0; w<W+2; w++ {
			out_map[h][w] = invalid
		}
	}
	for h:=0; h<H; h++{
		for w:=0; w<W; w++{
			out_map[h+1][w+1] = in_map[h][w] 
		}
	}
	return out_map
}

func bordersString(in_map [][]string, invalid string) [][]string{
	H, W := len(in_map), len(in_map[0])
	out_map := make([][]string, H+2)
	for h:=0; h<H+2; h++ {
		out_map[h] = make([]string, W+2)
		for w:=0; w<W+2; w++ {
			out_map[h][w] = invalid
		}
	}
	for h:=0; h<H; h++{
		for w:=0; w<W; w++{
			out_map[h+1][w+1] = in_map[h][w] 
		}
	}
	return out_map
}

func scanIntLine(len int) []int{
	arr := make([]int, len)
	for i:=0; i<len; i++{
		sc.Scan()
		tmp, err := strconv.Atoi(sc.Text())
		if err == nil{
			arr[i] = tmp
		}
	}
	return arr
}

func scanStringLine(len int) []string{
	arr := make([]string, len)
	for i:=0; i<len; i++{
		sc.Scan()
		arr[i] = sc.Text()
	}
	return arr
}

func scanIntSplit(len int) []int{
	arr := make([]int, len)
	sc.Scan()
	for i, v := range strings.Split(sc.Text(), " "){
		tmp, err := strconv.Atoi(v)
		if err == nil{
			arr[i] = tmp
		}
	}
	return arr
}

func maxInt(args... int) int{
	sort.Ints(args)
	return args[len(args)-1]
}

func main(){
	buf := make([]byte, 0)
    sc.Buffer(buf, 1000000009)
	var n int 
	fmt.Scan(&n)
	dp := make([][]int, 1003)
	for i:=0; i<1003; i++ {
		dp[i] = make([]int, 1003)
	}
	input_lines := scanStringLine(2*n)
	for i:=0; i<n; i++ {
		S, T := input_lines[2*i], input_lines[2*i+1]
		lenS, lenT := len(S), len(T)
		for i:=1; i<lenS+1; i++ {
			for j:=1; j<lenT+1; j++ {
				if S[i-1] == T[j-1] {
					dp[i][j] = dp[i-1][j-1]+1
				} else if S[i-1] != T[j-1] && dp[i-1][j] > dp[i][j-1] {
					dp[i][j] = dp[i-1][j]
				} else {
					dp[i][j] = dp[i][j-1]
				}
				// if S[i-1] == T[j-1] {
				// 	dp[i][j] = maxInt(dp[i-1][j-1]+1, dp[i-1][j], dp[i][j-1])
				// } else {
				// 	dp[i][j] = maxInt(dp[i-1][j], dp[i][j-1])
				// }
			}
		}
		fmt.Println(dp[lenS][lenT])
	}
}

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 max1 = 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]);
            }
            max1 = max(max1, c[i][j]);
        }
    }

    return max1;
}

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 <math.h>
#include <string>
#include <algorithm>
#include <set>
#include <queue>
#include <stack>
#include <utility>
#include <tuple>
using namespace std;

const double pi = acos(-1);
#define nyan cout<<"(=^•ω•^=)"<<endl;
#define int long long
#define rep(i,n) for(int i=0;i<n;i++)

int Q;
int dp[1100][1100];
// 1-leadingとして，
// dp[i][j] := sのi番目までの文字列とtのj番目までの文字列のLCSのサイズ

signed main(){
    cin>>Q;
    rep(q,Q){
        string s,t;
        cin>>s>>t;
        for(int i=0;i<=s.length();i++)dp[i][0]=0;
        for(int i=0;i<=t.length();i++)dp[0][i]=0;
        for(int i=1;i<=s.length();i++){
            for(int j=1;j<=t.length();j++){
                if(s[i-1]==t[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[s.length()][t.length()]<<endl;
    }
    return 0;
}

C++: #include <iostream>
#include <string>
#include <algorithm>
using namespace std;
 
static const long N = 1000;
 
long lcs(string X, string Y){
    long c[N + 1][N + 1];
    long m = X.size();
    long n = Y.size();
    long maxl = 0;
    X = ' ' + X;
    Y = ' ' + Y;
    for (long i = 1; i <= m; i++) c[i][0] = 0;
    for (long j = 1; j <= n; j++) c[0][j] = 0;
 
    for (long i = 1; i <= m; i++){
        for (long 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 = c[i][j];
        }
    }
 
    return maxl;
}
 
int main(){
    string s1, s2;
    long n;
    cin >> n;
    for (long i = 0; i < n; i++){
        cin >> s1 >> s2;
        cout << lcs(s1, s2) << endl;
    }
    return 0;
}

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

int h[1001][1001];
string A;
string B;

void f(int i, int j) {
    if (A.at(i) == B.at(j)) {
            h[i][j] = h[i-1][j-1] + 1;
    } else {
        h[i][j] = max(h[i][j-1], h[i-1][j]);
    }
}

int lcs(string A, string B) {
    for (int i = 1; i <= A.length()-1; ++i) {
        for (int j = 1; j <= B.length()-1; ++j) {
            f(i, j);
        }

    }
    return h[A.length()-1][B.length()-1];
}

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

    for (int i = 0; i < n; ++i) {
        cin >> A;
        cin >> B;
        A = " " + A;
        B = " " + B;
        int a = lcs(A, B);
        cout << a << endl;
    }

    return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;

int lcs(string a,string b){
  int c[1001][1001];
  for(int i=0;i<1001;i++){
      for(int j=0;j<1001;j++){
          c[i][j]=0;    
      } 
  }
  int m=a.size(),n=b.size();
  int mx=0;
  a=' '+a;
  b=' '+b;
  for(int i=1;i<=m;i++){
    for(int j=1;j<=n;j++){
      if(a[i]==b[j]){
	c[i][j]=c[i-1][j-1]+1;
      }else{
	c[i][j]=max(c[i-1][j],c[i][j-1]);
      }
      mx=max(mx,c[i][j]);
    }
  }
  return mx;
}


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

C++: #include<bits/stdc++.h>
using namespace std;
#define N 1050
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(){
  int q;cin>>q;
  while(q--){
    string a,b;cin>>a>>b;
    cout<<lcs(a,b)<<endl;
  }
  return 0;
}

C++: #include <iostream>

using namespace std;

int lcs(string X, string Y) {
  int memo[1010][1010];
  int maxl = 0;

  // 初期化、境界条件を考慮して場合分け
  for (int i = 0; i < X.size(); i++) {
    if (X[i] == Y[0]) {
      memo[i][0] = 1;
    } else {
      memo[i][0] = 0;
    }
  }

  for (int j = 0; j < Y.size(); j++) {
    if (X[0] == Y[j]) {
      memo[0][j] = 1;
    } else {
      memo[0][j] = 0;
    }
  }

  for (int i = 0; i < X.size(); i++) {
    for (int j = 0; j < Y.size(); j++) {
      if (X[i] == Y[j]) {
        memo[i][j] = memo[i-1][j-1] + 1;
      } else {
        memo[i][j] = max(memo[i-1][j], memo[i][j-1]);
      }
      maxl = max(maxl, memo[i][j]);
      //cout << i << "," << j << "," << X[i] << "," << Y[j] << "," << maxl << endl;
    }
  }
  return maxl;
}

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