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 "bits/stdc++.h"
using namespace std;

#define ASC(vec) vec.begin(), vec.end()		// 昇順ソート 例：sort(ASC(vec));
#define DESC(vec) vec.rbegin(), vec.rend()	// 降順ソート 例:sort(DESC(vec));
#define rep(i, n) for(int i = 0; i < (n); i++)
#define Rep(i, n) for(int i = 1; i < n; i++)

const int mod = 1000000007;
const int inf = (int)1e9 + 7;
const long long INF = 1LL << 60;

using ii = pair<int, int>;
using ll = long long;
using vi = vector<int>;
using vd = vector<double>;
using vb = vector<bool>;
using vl = vector<ll>;
using vs = vector<string>;
using vvi = vector<vector<int>>;
using vvl = vector<vector<ll>>;
using vvb = vector<vector<bool>>;
using vii = vector<pair<int, int>>;

template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }

ll GCD(ll a, ll b) { return b ? GCD(b, a % b) : a; }
ll LCM(ll a, ll b) { return (a * b) / GCD(a, b); }
int round_int(int a, int b) { return (a + (b - 1)) / b; }

// 素因数分解; 返り値は(素数, 乗数)のvector配列
vector<pair<ll, int>> factorize(ll n) {
	vector<pair<ll, int>> res;
	for (ll i = 2; i * i <= n; ++i) {
		if (n % i) continue;
		res.emplace_back(i, 0);
		while (n % i == 0) {
			n /= i;
			res.back().second++;
		}
	}
	if (n != 1) res.emplace_back(n, 1);
	return res;
}

constexpr array<int, 9> dx = { 0, 1, 0, -1, -1, 1, 1, -1, 0 };
constexpr array<int, 9> dy = { 1, 0, -1, 0, 1, 1, -1, -1, 0 };
constexpr auto MAX = 100000;

// ──────────────────────────────────────────────────────────────────

int dp[1010][1010];

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

	rep(i, n) {
		string s, t;
		cin >> s >> t;

		memset(dp, 0, sizeof(dp));
		rep(i, s.size()) {
			rep(j, t.size()) {
				if (s[i] == t[j]) dp[i + 1][j + 1] = max(dp[i + 1][j + 1], dp[i][j] + 1);
				dp[i + 1][j + 1] = max({ dp[i + 1][j + 1], dp[i + 1][j], dp[i][j + 1] });
			}
		}
		cout << dp[s.size()][t.size()] << endl;
	}
}

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

using namespace std;

int main(){
  int n;
  int k;
  int count;
  int min;
  cin>>n;
  char X[1001];
  char Y[1001];
  for(int i=0;i<n;i++){
    cin>>X;
    cin>>Y;
    k=0;
    count=0;
    min=100000;
    for(int a=0;X[a]!='\0';a++){
      for(int i=a;X[i]!='\0';i++){
	for(int j=k;Y[j]!='\0';j++){
	  if(X[i]==Y[j]){
	    count++;
	    k=j;
	    break;
	  }
	}
      }
      if(min>count)min=count;
    }
    cout<<min<<endl;
    
  }
  return 0;
}

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

using namespace std;

int main() {
    int a;
    string s,t;
    cin >> a;

    for(int ai = 0; ai < a; ai++) {
        cin >> s >> t;
        int n = s.length(), m = t.length();

        int dp[n+1][m+1];
        fill_n(dp[0], (n+1)*(m+1), 0);
        for(int i = 0; i < n; i++) {
            for(int j = 0; j < m; j++) {
                if(s[i] == t[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[n][m] << endl;
    }
}

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

using namespace std;

int larger(int x, int y){
	if(x > y){
		return x;
	}
	return y;
}

int main(){
	int Q;
	cin >> Q;
	for(int i = 0; i < Q; i++){
		string X, Y;
		cin >> X >> Y;
		int lenX = X.size();
		int lenY = Y.size();
		int dp[lenX+1][lenY+1];
		for(int j = 0; j <= lenX; j++){
			for(int k = 0; k <= lenY; k++){
				dp[j][k] = 0;
			}
		}
		for(int j = 0; j < lenX; j++){
			for(int k = 0; k < lenY; k++){
				if(X[j] == Y[k]){
					dp[j+1][k+1] = dp[j][k] + 1;
				}
				else{
					dp[j+1][k+1] = larger(dp[j+1][k], dp[j][k+1]);
				}
			}
		}
		cout << dp[lenX][lenY] << "\n";
	}
}

C++: #include <stdio.h>
#include <string.h>
#define rep(i, n) for(int i = 0; i < n; ++i)
#define repi(i, n) for(int i = 1; i < n; ++i)

int max(int a, int b) {
  return a > b ? a : b;
}

int main(void) {
  int n;
  scanf("%d", &n);
  rep(i, n) {
    char x[1500], y[1500], h, w;
    scanf("%s", x);
    scanf("%s", y);
    h = strlen(x), w = strlen(y);
    int dp[h][w], len[w], maxs = 0;
    rep(j, h) rep(k, w) dp[j][k] = 0;
    rep(j, w) if(x[0] == y[j]) dp[0][j] = 1;
    len[0] = 0;
    repi(j, w) len[j] = max(dp[0][j - 1], len[j - 1]);
    repi(j, h) {
      rep(k, w) if(x[j] == y[k]) {
        dp[j][k] = len[k] + 1;
        if(maxs < dp[j][k]) maxs = dp[j][k];
      }
      repi(k, w) len[k] = max(dp[j][k - 1], max(len[k], len[k - 1]));
      /*rep(k, w) printf("%d ", len[k]);
      printf("\n");*/
    }
    /*printf("\n");
    rep(j, h) {
      rep(k, w) printf("%d ", dp[j][k]);
      printf("\n");
    }*/
    printf("%d\n", maxs);
  }
  return 0;
}