Go: package main

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

type Position struct {
	X int
	Y int
}

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	n, err := nextInt(sc)
	if err != nil {
		panic(err)
	}
	for i := 0; i < n; i++ {
		strX := nextText(sc)
		strY := nextText(sc)
		fmt.Println(calcLcs(strX, strY))
	}
}

func calcLcs(strX, strY string) int {
	return lcs(strX, strY, Position{0, 0}, make(map[Position]int))
}

func lcs(strX string, strY string, position Position, memo map[Position]int) int {
	if position.X >= len(strX) || position.Y >= len(strY) {
		return 0
	}
	if v, ok := memo[position]; ok {
		return v
	}
	if strX[position.X] == strY[position.Y] {
		result := lcs(strX, strY, Position{position.X + 1, position.Y + 1}, memo)
		memo[position] = result + 1
		return memo[position]
	} else {
		result1 := lcs(strX, strY, Position{position.X + 1, position.Y}, memo)
		result2 := lcs(strX, strY, Position{position.X, position.Y + 1}, memo)
		var result int
		if result1 > result2 {
			result = result1
		} else {
			result = result2
		}
		memo[position] = result
		return result
	}
}

func nextInt(sc *bufio.Scanner) (int, error) {
	sc.Scan()
	return strconv.Atoi(sc.Text())
}

func nextText(sc *bufio.Scanner) string {
	sc.Scan()
	return sc.Text()
}

C++: #include <bits/stdc++.h>
using namespace std;
#define Rep(i, n) for (int i = 0; i < (int)(n); i++)
#define BitRep(i, n) for (int i = 0; i < (int)(1 << n); i++)
#define Sum(vec) accumulate(vec.begin(), vec.end(), 0)
#define Sort(vec) sort(vec.begin(), vec.end())
#define Reverse(vec) reverse(vec.begin(), vec.end())
#define Next_permutation(vec) next_permutation(vec.begin(), vec.end())

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<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 <bits/stdc++.h>
using namespace std;
#define rep(i,n) for (int (i)=(0);(i)<(int)(n);++(i))
using ll = long long;
using P = pair<int, int>;
using namespace std;

template<class T> void vin(vector<T>& v, int n) {
    v.resize(n);
    for (int i = 0; i < n; ++i) {
        cin >> v[i];
    }
}

string a, b;
int dp[2000][2000];

int solve(int xi=0, int yi=0) {
    if (xi == a.size() and yi == b.size()) {
        return 0;
    }
    int& res = dp[xi][yi];
    if (~res) return res;

    if (a[xi] == b[yi]) {
        res = solve(xi+1, yi+1) + 1;
    }
    else {
        if (xi < a.size()) res = max(res, solve(xi+1, yi));
        if (yi < b.size()) res = max(res, solve(xi, yi+1));
    }
    return res;
}

int main() {
    int n;
    cin >> n;
    while (n--) {
        cin >> a >> b;
        fill(dp[0], dp[2000], -1);
        cout << solve() << endl;
    }
    return 0;
}

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

using namespace std;

int N=1000;

int LCS(string x,string y){
	int c[N+1][N+1],LCSlen=0;
	int m=x.size();
	int n=y.size();
	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]);
			LCSlen=max(LCSlen,c[i][j]);
		}
	}
	return LCSlen;
}

int main(){
	char x[1000],y[1000];
	string xst,yst;
	int n;
	scanf("%d",&n);
	for(int i=0;i<n;i++){
		scanf("%s",x);
		scanf("%s",y);
		xst=x;
		yst=y;
		printf("%d\n",LCS(x,y));
	}
}

C++: #include <algorithm>
#include <cassert>
#include <cmath>
#include <cstdio>
#include <deque>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <string>
#include <vector>

using namespace std;

#define pb push_back

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> i_i;
typedef pair<i_i, int> p_i;
typedef vector<int> vi;
typedef vector<vector<int> > vvi;
template<class T> using vv=vector<vector< T > >;

int main() {
  int t;
  cin >> t;
  vi results;
  for (int dataset = 0 ; dataset < t ; dataset++) {
    string a, b;
    cin >> a;
    cin >> b;
    vvi len(a.length()+1, vi(b.length(), 0));
    for (int ia = 1 ; ia <= a.length() ; ia++) {
      for (int ib = 1 ; ib <= b.length() ; ib++) {
        if (a[ia] == b[ib]) {
          len[ia][ib] = len[ia-1][ib-1]+1;
        } else {
          len[ia][ib] = max(len[ia][ib-1], len[ia-1][ib]);
        }
      }
    }
    results.pb(len[a.length()][b.length()]);
  }

  for (int it = 0 ; it < t ; it++) {
    printf("%d\n", results[it]);
  }

  return 0;
}

C++: #define _USE_MATH_DEFINES

#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <cmath>
#include <algorithm>
#include <vector>
#include <queue>
#include <map>
#include <list>

long long int INF = 1e18;
using namespace std;

typedef pair<long long int, long long int> P;

long long int DP[1001][1001] = {};

int main(){
	
	int n;
	cin >> n;
	
	for(int loop = 0; loop < n; loop++){
		
		string str1, str2;
		cin >> str1 >> str2;
		
		for(int i = 1; i <= str1.size(); i++){
			for(int j = 1; j <= str2.size(); j++){
				if(str1[i - 1] == str2[j - 1]){
					DP[i][j] = max(max(DP[i - 1][j - 1] + 1, DP[i - 1][j]), DP[i][j - 1]);
				}else{
					DP[i][j] = max(DP[i - 1][j], DP[i][j - 1]);
				}
			}
		}
		
		cout << DP[str1.size()][str2.size()] << endl;
	}
	return 0;
}

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

using namespace std;


long long L[1010][1010] {0};
int main(){
  int Q;
  cin >> Q;
  for(int i = 0; i < Q; i++){
    string X, Y;
    cin >> X >> Y;
    int xlen = X.length();
    int ylen = Y.length();
    for(int i = 1; i<= xlen; i++){
      for(int k = 1; k <= ylen; k++){
	if(X[i-1] == Y[k-1]){
	  L[i][k] = 1 + L[i-1][k-1];
	}else{
	  L[i][k] = max(L[i][k-1], L[i-1][k]);
	}
      }
    }

    cout << L[xlen][ylen] << endl;
  }

}

C++: #include <iostream>
#include <string>
using namespace	std;
int main(){

  int n;
  string s1,s2;
  cin>>n;
  for(int i=0;i<n;i++){
    cin>>s1>>s2;
    int dp[1001][1001]={};
    for(int j=1;j<=s2.size();j++){
      for(int k=1;k<=s1.size();k++){
        if(s1[k-1]==s2[j-1]) dp[j][k]=dp[j-1][k-1]+1;
        else dp[j][k]=max(dp[j-1][k],dp[j][k-1]);
      }
    }
    cout<<dp[s2.size()][s1.size()]<<endl;
  }
  return 0;

}