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 <vector>
#include <map>
#include <algorithm>
#include <queue>
#include <string>
#define REP(i,a,b) for (int i = a; i < (b); i++)
#define sz(t) int(t.size())
#define INF 1000000000
const int DIV = 1000000000 + 7;
using namespace std;
typedef long long ll;

int solve(string x, string y) {
    int dp[1050][10050];
    x = ' ' + x;
    y = ' ' + y;
    int lx = x.size();
    int ly = y.size();
    REP(i, 0, lx) dp[0][i] = 0;
    REP(i, 0, ly) dp[i][0] = 0;
    int ans = 0;
    REP(i, 1, ly) {
        REP(j ,1, lx) {
            if (y[i] == x[j]) {
                dp[i][j] = dp[i - 1][j - 1] + 1;
            } else {
                dp[i][j] = max(dp[i][j - 1], dp[i - 1][j]);
            }  
            ans = max(ans, dp[i][j]);
        }
    }

    return ans;
}

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

    REP(i, 0, n) {
        string x, y;
        cin >> x;
        cin >> y;
        cout << solve(x, y) << endl;
    }
}

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

int Longest(string x, string y) {
  int L[1001][1001];
  int maxl = -1;
  int xlen = x.size();
  int ylen = y.size();

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

  for (int i = 1; i <= xlen; i++) L[i][0] = 0;
  for (int j = 1; j <= ylen; j++) L[0][j] = 0;

  for (int i = 1; i <= xlen; i++) {
    for (int j = 1; j <= ylen; j++) {
      if (x[i] == y[j]) {
        L[i][j] = L[i-1][j-1] + 1;
      } else {
        L[i][j] = max(L[i][j-1], L[i-1][j]);
        }
      maxl = max(maxl, L[i][j]);
    }
  }

  return maxl;
}

int main() {
  string X, Y;
  int n;
  cin >> n;

  for (int i = 0; i < n; i++) {
    cin >> X;
    cin >> Y;
    cout << Longest(X, Y) << endl;
  }

  


  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define rep(i,n,x) for(int i=n;i<x;i++)
const int MAX_N = 1000;

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

    int dp[MAX_N+1][MAX_N+1];

    while(q > 0){
        string x, y; cin >> x >> y;

        int X = x.size(), Y = y.size();
        rep(i, 0, X){
            rep(j, 0, Y){
                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]);
            }
        }

        cout << dp[X][Y] << endl;

        q--;
    }

    return 0;
}

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

//#define int long long
//struct Fast {Fast(){cin.tie(0);ios::sync_with_stdio(0);}} fast;
//const int MOD = 1e9 + 7;
using intpair = pair<int, int>;

#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define reps(i, n, m) for (int i = (int)(n); i <= (int)(m); i++)
#define ALL(obj) (obj).begin(), (obj).end()
#define rALL(obj) (obj).rbegin(), (obj).rend()
#define ceiv(a, b) ((int)((a) + (b) - 1)/(int)(b))

int dp[1001][1001];

inline bool chmax(int &a, int b){
    if(a < b) a = b;
    return a < b;
}

signed main() {
    int Q; cin >> Q;
    while(Q--){
        string s, t;
        cin >> s >> t;
        int n = (int)s.length();
        int m = (int)t.length();
        
        rep(i,n+1)rep(j,m+1) dp[i][j] = 0;
        
        reps(i,1,n)reps(j,1,m){
            dp[i][j] = max(dp[i-1][j], dp[i][j-1]);
            if(s[i-1] == t[j-1]){
                chmax(dp[i][j], dp[i-1][j-1]+1);
            }
        }
        
        cout << dp[n][m] << endl;
    }
}

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

using namespace std;

static const int N = 1000;

static int lcs(string& s1, string& s2) {
	int table[N + 1][N + 1];
	int m = s1.size();
	int n = s2.size();
	int max_len = 0;
	s1 = ' ' + s1;
	s2 = ' ' + s2;

	for (int i = 0; i <= m; i++) table[i][0] = 0;
	for (int j = 0; j <= m; j++) table[0][j] = 0;
	for (int i = 1; i <= m; i++) {
		for (int j = 1; j <= n; j++) {
			if (s1[i] == s2[j]) {
				table[i][j] = table[i - 1][j - 1] + 1;
			}
			else {
				table[i][j] = max(table[i - 1][j], table[i][j - 1]);
			}

			max_len = max(table[i][j], max_len);
		}
	}

	return max_len;
}

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

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

	return 0;
}

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

int Longest(string x, string y) {
  int L[1001][1001];
  int maxl = -1;
  int xlen = x.size();
  int ylen = y.size();

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

  for (int i = 1; i <= xlen; i++) L[i][0] = 0;
  for (int j = 1; j <= ylen; j++) L[0][j] = 0;

  for (int i = 1; i <= xlen; i++) {
    for (int j = 1; j <= ylen; j++) {
      if (x[i] == y[j])
        L[i][j] = L[i-1][j-1] + 1;
      else
        L[i][j] = max(L[i][j-1], L[i-1][j]);

      maxl = max(maxl, L[i][j]);
    }
  }

  return maxl;
}

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

  cin >> n;

  for (int i = 0; i < n; i++) {
    cin >> X;
    cin >> Y;
    cout << Longest(X, Y) << endl;
  }

  


  return 0;
}