Go: package main

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

// I/O
type Scanner struct {
	sc *bufio.Scanner
}

func NewScanner() *Scanner {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	sc.Buffer(make([]byte, 1024), int(1e+9))
	return &Scanner{sc}
}

func (s *Scanner) nextStr() string {
	s.sc.Scan()
	return s.sc.Text()
}

func (s *Scanner) nextInt() int {
	i, e := strconv.Atoi(s.nextStr())
	if e != nil {
		panic(e)
	}
	return i
}

func (s *Scanner) nextFloat() float64 {
	f, e := strconv.ParseFloat(s.nextStr(), 64)
	if e != nil {
		panic(e)
	}
	return f
}

func (s *Scanner) nextRuneSlice() []rune {
	return []rune(s.nextStr())
}

func (s *Scanner) nextIntSlice(n int) []int {
	res := make([]int, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextInt()
	}
	return res
}

func (s *Scanner) nextFloatSlice(n int) []float64 {
	res := make([]float64, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextFloat()
	}
	return res
}

// Arithmetic
func max(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m < i {
			m = i
		}
	}
	return m
}

func min(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m > i {
			m = i
		}
	}
	return m
}

func abs(x int) int {
	if x > 0 {
		return x
	}
	return -x
}

func pow(x, y int) int {
	res := 1
	for i := 0; i < y; i++ {
		res *= x
	}
	return res
}

func ceil(a, b int) int {
	if a%b == 0 {
		return a / b
	} else {
		return a/b + 1
	}
}

// Sort
type RuneSlice []rune

func (a RuneSlice) Len() int           { return len(a) }
func (a RuneSlice) Less(i, j int) bool { return a[i] < a[j] }
func (a RuneSlice) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }

// Main
func main() {
	sc := NewScanner()
	wtr := bufio.NewWriter(os.Stdout)
	Q := sc.nextInt()
	for q := 0; q < Q; q++ {
		X, Y := sc.nextStr(), sc.nextStr()
		xLen, yLen := len(X), len(Y)
		dp := make([][]int, xLen+1)
		for i := 0; i <= xLen; i++ {
			dp[i] = make([]int, yLen+1)
		}
		for x := 0; x <= xLen; x++ {
			for y := 0; y <= yLen; y++ {
				if x == 0 || y == 0 {
					dp[x][y] = 0
				} else if X[x-1] == Y[y-1] {
					dp[x][y] = dp[x-1][y-1] + 1
				} else {
					dp[x][y] = max(dp[x-1][y], dp[x][y-1])
				}
			}
		}
		fmt.Fprintln(wtr, dp[xLen][yLen])
	}

	wtr.Flush()
}

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

using namespace std;

int lcs (string x, string y) {

    int m, n, c[1001][1001], i, j, maxl = 0;

    m = x.size();
    n = y.size();

    x = ' ' + x;
    y= ' ' + y;

    for (i = 0; i <= m; i++) {
        c[i][0] = 0;
    }
    for (j = 1; j <= n; j++) {
        c[0][j] = 0;
    }

    for (i = 1; i <= m; i++) {
            for (j = 1; j <= n; j++) {

                if (x[i - 1] == y[j - 1]) {
                    c[i][j] = c[i - 1][j - 1] + 1;
                } else {
                    c[i][j] = max (c[i - 1][j], c[i][j - 1]);
                }

                maxl = max (max, c[i][j]);

            }
    }

    return maxl;

}



int main () {

    int N, i;
    string x, y;

    cin >> N;

    for (i = 0; i < n; i++) {
        cin >> x >> y;
        cout << lcs (x, y) << endl;

    }

    return 0;

}

C++: #include<iostream>
#include<string>
#include<algorithm>
using namespace std;
static const int N =1000;
int lcs(string, 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++){
    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] = mx(c[i - 1][j], c[i][j = 1]);
      }
      maxl = max(mxl, 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 << lcs8s1, 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();
  
  for (int i = 0; i < m; i++) {
    for (int j = 0; j < n; j++) {
      if (X[i] == Y[j]) 
        if (i == 0 || j == 0) 
          c[i][j] = 1;
        else 
          c[i][j] = c[i - 1][j - 1] + 1;
      else
        if (i != 0 && j != 0) 
          c[i][j] = max(c[i][j - 1], c[i - 1][j]);
        else
          c[i][j] = 0;
    }
  }
  return c[m - 1][n - 1];
}

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;

int lcs(string X, string Y){
  int c[1001][1001];
  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>
#define rep(i, n) for(int i = 0; i < (n); ++i)

using namespace std;
using ll = long long;
using v1 = vector<int>;
using vl = vector<long long>;
using v2 = vector<vector<int>>;
using v3 = vector<vector<char>>;

int N, M;
string s1, s2;

int lcs(string x, string y){
	int c[1001][1001];
	N = s1.size();
	M = s2.size();
	int maxl = 0;
	x = ' ' + x;
	y = ' ' + y;
	rep(i, N) c[i][0] = 0;
	rep(i, M) 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]);
			}
			maxl = max(maxl, c[i][j]);
		}
	}
	return maxl;
}

int main(){
	int n;
	cin >> n;
	rep(i, n){
		cin >> s1 >> s2;
		cout << lcs(s1,s2) << endl;
	}
}

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(int argc, char const* argv[])
{
    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>
#define rep(i,n) for (int i = 0; i < (n); i++)
using namespace std;
typedef long long ll;

int dp[1010][1010];

int main(){
    int q; cin >> q;
    rep(i,q){
        string x,y; cin >> x >> y;
        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;
}