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 <sstream>
#include <fstream>
#include <string>
#include <vector>
#include <deque>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <unordered_map>
#include <algorithm>
#include <functional>
#include <utility>
#include <bitset>
#include <cmath>
#include <cstdlib>
#include <ctime>
#include <cstdio>
#include <cstring>
using namespace std;

typedef long long ll;
#define rep(i, a, b) for (ll i=(a); i<(b); i++)
#define all(obj) (obj).begin(), (obj).end()
#define fi first
#define sc second
#define pb push_back
#define str to_string
const ll INF = 1e18;
const ll MOD = 1e9 + 7;
void chmax(ll &a, ll b) { a = max(a, b); }
void chmin(ll &a, ll b) { a = min(a, b); }

ll dp[1010][1010];

ll LCS(string a, string b) {
    int N = a.size();
    int M = b.size();
    memset(dp, 0, sizeof(dp));

    rep(i, 0, N+1) rep(j, 0, M+1) {
        if (i < N) {
            chmax(dp[i+1][j], dp[i][j]);
        }
        if (j < M) {
            chmax(dp[i][j+1], dp[i][j]);
        }
        if (i < N && j < M && a[i] == b[j]) {
            chmax(dp[i+1][j+1], dp[i][j]+1);
        }
    }
    return dp[N][M];
}

int main() {
    int Q;
    string a, b;
    cin >> Q;
    rep(i, 0, Q) {
        cin >> a;
        cin >> b;
        cout << LCS(a, b) << endl;
    }
    return 0;
}

C++: #include <algorithm>
#include <iostream>
#include <string>
#include <vector>
#include <utility>
#include <queue>
#include <cmath>
#include <set>
#include <iomanip>

using namespace std;

typedef long long ll;

int get_LCS(string x, string y){
  int nx = x.size(), ny = y.size();
  int dp[nx+1][ny+1];
  for(int i=0;i<=ny;i++) dp[0][i] = 0;
  for(int i=0;i<=nx;i++) dp[i][0] = 0;
  for(int i=1;i<=nx;i++){
    for(int j=1;j<=ny;j++){
      if(x[i-1] == y[j-1]) dp[i][j] = dp[i-1][j-1] + 1;
      else dp[i][j] = max(dp[i][j-1], dp[i-1][j]);
    }
  }
  /*for(int i=1;i<=nx;i++){
    for(int j=1;j<=ny;j++){
      cout << dp[i][j] << " ";
    }
    cout << endl;
  }*/
  return dp[nx][ny];
}

int main(){
  cin.tie(0);
  ios_base::sync_with_stdio(false);
  int q; cin >> q;
  for(int i=0;i<q;i++){
    string x, y; cin >> x >> y;
    cout << get_LCS(x, y) << endl;
  }
}

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

using namespace std;

signed main() {
  int n; cin >> n;
  string x,y;
  while(n--){
    cin >> x >> y;
    vector<vector<int> > dp(x.size()+1,vector<int>(y.size()+1));
    for(int i=0;i<x.size();++i){
      for(int j=0;j<y.size();++j){
	if(x[i]==y[j]) dp[i+1][j+1]=dp[i][j]+1;
	else dp[i+1][j+1]=max(dp[i+1][j],dp[i][j+1]);
      }
    }
    cout << dp[x.size()][y.size()] << 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=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<cstdio>
#include<string>
#include<algorithm>
#define Lens 1005

using namespace std;
string x, y;
int C[Lens][Lens];
int N;

int com(string x,string y)
{
	int m = x.length();
	int n = y.length();
	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]);
			}
		}
	return C[m][n];

}

int main()
{
	cin >> N;
	for (int i = 0; i < N; i++)
	{
		cin >> x >> y;
		int ans=com(x, y);
		cout << ans << endl;
	}


	return 0;
}

C++: #include<algorithm>
#include<iostream>
#include<cstdlib>
#include<cstring>
#include<cstdio>
#include<vector>
#include<queue>
#include<stack>
#include<cmath>
#include<list>
#include<map>
#include<set>
using namespace std;

typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<string> VS;
typedef pair<int,int> PII;
typedef long long LL;

#define d(x)  cout<<#x<<" = "<<(x)<<endl;
#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 REACH(i,c) for(typeof((c).rbegin()) i=(c).rbegin(); i!=(c).rend(); ++i)
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define SORT(c,n) sort(c,c+n)
#define VSORT(c) sort((c).begin(),(c).end())
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)  FOR(i,0,n)
#define DFOR(i,b,a) for(int i=(b)-1;i>=(a);--i)
#define DREP(i,n) DFOR(i,n,0)
#define INF 2000000000

const double EPS = 1e-10;
const double PI  = acos(-1.0);
////////////////////////////////////////////////
int q;
string X,Y;
int a[1010][1010];



int main()
{
	cin>>q;
	REP(i,q)
	{
		cin>>X>>Y;
		int m=SZ(X);
		int n=SZ(Y);
		X=' '+X;
		Y=' '+Y;
		FOR(i,1,m+1)
		{
			FOR(j,1,n+1)
			{
				if(X[i]==Y[j])a[i][j]=a[i-1][j-1]+1;
				else a[i][j]=max(a[i-1][j],a[i][j-1]);
			}
		}
		cout<<a[m][n]<<endl;
	}
	return 0;
}