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 <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
const int maxx = 1010;
int c[maxx][maxx];

int lcs(char s1[],char s2[]) {
    int m = strlen(s1), n = strlen(s2);
    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 (s1[i] == s2[j])
            c[i+1][j+1] = c[i][j] + 1;
            else
            c[i+1][j+1] = max(c[i][j+1], c[i + 1][j]);
        }
    }
    return c[m][n];
}
int main()
{
    char s1[maxx], s2[maxx];
    int t;
    scanf("%d", &t);
    for (int i = 0; i < t; i++) {
        scanf("%s %s", s1, s2);
        printf("%d\n",lcs(s1,s2));
    }
    
    return 0;
}

C++: #include <iostream>
#include <string>
#define repi(i,a,b) for(int i=(a);i<(b);++i)
#define rep(i,a) repi(i,0,a)
#define clr(a,v) memset((a),(v),sizeof(a))

int q;
int dp[1000][1000];
std::string s, t;

int rec( int i, int j )
{
  int &ret = dp[i][j];

  if( ~ret )
    return ret;

  if( i == s.size() || j == t.size() )
    return 0;

  ret = 0;

  if( s[i] == t[j] )
    ret = std::max( ret, rec( i+1, j+1 )+1 );

  ret = std::max( { ret, rec( i+1, j ), rec( i, j+1 ) } );

  return ret;
}

int main()
{
  scanf( "%d", &q );
  while( q-- )
  {
    std::cin >> s >> t;

    clr( dp, -1 );

    std::cout << rec( 0, 0 ) << std::endl;
  }

  return 0;
}

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

C++: #include <cstdio>
#include <iostream>
#include <algorithm>
#include <cstring>
using namespace std;
const int maxx=1010;

int main (){
	int dp[maxx][maxx];
	string s,p;
	int q;
	cin>>q;
	while(q--){
		cin>>s>>p;
		for(int i=0;i<=s.size();i++){
			for(int j=0;j<=p.size();j++){
				if(i==0||j==0) dp[i][j]=0;
				else if(s[i]==p[j]) 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.size()][p.size()]<<endl;
	}
	return 0;
}

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

using namespace std;

const int max_size = 1001;

int main() {
  int n_input; // number of inputs of pairs of sequences
  cin >> n_input;

  for (int i = 0; i < n_input; i++) {
    string seq1, seq2;
    cin >> seq1 >> seq2;
    int seq1_len = seq1.length(), seq2_len = seq2.length();
    int grid[max_size][max_size] = {{0}};
    for (int rowi = 1; rowi <= seq1_len; rowi++) {
      for (int coli = 1; coli <= seq2_len; coli++) {
	if (seq1[rowi - 1] == seq2[coli - 1]) {
	  grid[rowi][coli] = grid[rowi - 1][coli - 1] + 1;
	} else {
	  int above_grid = grid[rowi - 1][coli], left_grid = grid[rowi][coli - 1];
	  grid[rowi][coli] = (above_grid >= left_grid)?above_grid:left_grid;
	}
      }
    }
    cout << grid[seq1_len][seq2_len] << endl;
  }
}

C++: #include<bits/stdc++.h>
#define rep(i,n)for(int i=0;i<n;i++)
using namespace std;

int dp[1001][1001];
int main() {
	int q; scanf("%d", &q);
	rep(i, q) {
		string x, y; cin >> x >> y;
		rep(i, x.size())rep(j, y.size()) {
			if (x[i] == y[j])dp[i + 1][j + 1] = dp[i][j] + 1;
			else dp[i + 1][j + 1] = max(dp[i][j + 1], dp[i + 1][j]);
		}
		printf("%d\n", dp[x.size()][y.size()]);
	}
}

C++: #include <iostream>
#include <string>
using namespace std;
static const int MAX = 1001;

void lcs(string X, string Y) {
	int dp[MAX][MAX];  
	int i,j;

	int xLength = X.size();
	int yLength = Y.size();


	// initialize dp[][]
	for (i = 1; i <= xLength; i++)
		dp[i][0] = 0;
	for (i = 1; i <= yLength; i++)
		dp[0][i] = 0;

	for (i = 1; i <= xLength; i++){
		for (j = 1; j <= yLength; j++){
			if (X[i] == Y[j]) {
				dp[i][j] = dp[i-1][j-1] + 1;
			}else {
				dp[i][j] = max(dp[i-1][j], dp[i][j-1]);
			}
		}
	}

	// testing code: print out the dp[][]
	// cout << "j";
	// for (j = 1; j <= yLength; j++)
	// 	cout << ' ' << j ;
	// cout << endl;
		

	// for (i = 1; i <= xLength; i++){
	// 	cout << i << '.';
	// 	for (j = 1; j <= yLength; j++){
	// 		cout << dp[i][j] << ' ';
	// 	}
	// 	cout << endl;
	// }

	cout << dp[xLength][yLength] << endl;
}

int main() {
	int n , i;
	string X, Y;

	cin >> n;
	for (i = 0 ; i < n; i++ ) {
		cin >> X;
		cin >> Y;
		lcs(X, Y);
	}

	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;
}