Go: package main

import (
	. "fmt"
    "math"
)

// func init() { Println("----------------------------------------") }

func main() {
    const L_MAX = 1003

	var q int
	Scanf("%d", &q)
	X := make([]string, 0, 150)
	Y := make([]string, 0, 150)
	for i := 0; i < 2 * q; i++ {
	    var tmp string
	    Scanf("%s", &tmp)

	    if i % 2 == 0 {
	        X = append(X, tmp)
	    } else {
	        Y = append(Y, tmp)
	    }
	}

    for i := 0; i < q; i++ {
        dp := make([][]int, L_MAX)
        for k, _ := range dp {
            dp[k] = make([]int, L_MAX)
        }

        x, y := X[i], Y[i]

        // init
        isXFound := false
        for c := 0; c < len(x); c++ {
            if isXFound || y[0] == x[c] {
                dp[0][c] = 1
                isXFound = true
            }
        }
        isYFound := false
        for r := 0; r < len(y); r++ {
            if isYFound || x[0] == y[r] {
                dp[r][0] = 1
                isYFound = true
            }
        }

        for r := 1; r < len(y); r++ {
            for c := 1; c < len(x); c++ {
                // dp[r][c]
                if x[c] == y[r] {
                    dp[r][c] = int(math.Max(float64(dp[r - 1][c - 1] + 1), float64(dp[r][c])))
                }

                dp[r][c] = int(math.Max(float64(dp[r][c]), math.Max(float64(dp[r - 1][c]), float64(dp[r][c - 1]))))
            }
        }
        Println(dp[len(y) - 1][len(x) - 1])

        // LCSも求めておく
        // ans := ""
        // r, c := len(y) - 1, len(x) - 1
        // for r >= 0 && c >= 0 {
        //     if y[r] == x[c] {
        //         ans = string(x[c]) + ans
        //         r--
        //         c--
        //     } else {
        //         if dp[r - 1][c] > dp[r][c - 1] {
        //             r--
        //         } else {
        //             c--
        //         }
        //     }
        // }
        // Println(ans)
    }
}

C++: # include <bits/stdc++.h>
# define rep(i, n) for(int i=0, i##_len=(n); i<i##_len; ++i)
# define reps(i, n) for(int i=1, i##_len=(n); i<=i##_len; ++i)
# define rrep(i, n) for(int i=((int)(n)-1); i>=0; --i)
# define rreps(i, n) for(int i=((int)(n)); i>0; --i)
# define range_for(i, b, e) for(int i=(b), i##_len=(e); i<i##_len; ++i)
# define step(n) rep(_, n)
# define ALL(x) (x).begin(), (x).end()
# define RALL(x) (x).rbegin(), (x).rend()
# define Unique(a) a.erase(unique(ALL(a)), a.end())
# define pb push_back
# define len(x) ((int)(x).size())
# define optimize_cin() cin.tie(0); ios::sync_with_stdio(false)
# define debug(x) std::cerr<<#x<<": "<<(x)<<endl;
# define LINT_MAX (LLONG_MAX)
# define LINT_MIN (LLONG_MIN)
# define cauto const auto
using namespace std;
template <class Type> inline constexpr Type Square(Type x) { return x * x; }
template <class Type> inline constexpr bool InRange(const Type& x, const Type& fst, const Type& lst) { return (fst <= x) && (x < lst); }
template<class Integer> inline bool chmax(Integer &a, Integer b) { return a < b && (a = b, true); }
template<class Integer> inline bool chmin(Integer &a, Integer b) { return a > b && (a = b, true); }
template<class Integer>bool IsOdd(Integer &n) { return n & 1; }
template<class Integer>bool IsEven(Integer &n) { return !(n & 1); }
long long gcd(long long a, long long b) { while(b){ long long A = a; (a = b), (b = A % b); } return a; }
long long lcm(long long a, long long b) { return a / gcd(a, b) * b; }
int ctoi(const char c) { return ('0' <= c && c <= '9') ? (c - '0') : -1; }
string YesNo(bool b) { return b ? "Yes" : "No"; }
string YESNO(bool b) { return b ? "YES" : "NO"; }
string yesno(bool b) { return b ? "yes" : "no"; }
void _cin(){} template <class Head, class... Tail> void _cin(Head&& head, Tail&&... tail){ cin >> head; _cin(forward<Tail>(tail)...); }
#define Cin(Type, ...) Type __VA_ARGS__; _cin(__VA_ARGS__)
#define Cinv(Type, xs, n) vector<Type> xs(n); rep(i, n) cin >> xs[i]
#define Cinv2(Type, xs, ys, n) vector<Type> xs(n), ys(n); rep(i, n) cin >> xs[i] >> ys[i]
#define Cinv3(Type, xs, ys, zs, n) vector<Type> xs(n), ys(n), zs(n); rep(i, n) cin >> xs[i] >> ys[i] >> zs[i]
#define Cinvv(Type, xs, h, w) vector<vector<Type>> xs(h, vector<int>(w)); rep(i, h) rep(j, w) cin >> xs[i][j]
void Print() { cout << endl; }
template <class Head, class... Tail> void Print(Head&& head, Tail&&... tail) { cout << head; if (sizeof...(tail) != 0) cout << " "; Print(forward<Tail>(tail)...); }
template <class Type> void Print(vector<Type> &vec) { for (auto& a : vec) { cout << a; if (&a != &vec.back()) cout << " "; } cout << endl; }
template <class Type> void Print(vector<vector<Type>> &df) { for (auto& vec : df) { Print(vec); } }
void Debug() { cerr << endl; }
template <class Head, class... Tail> void Debug(Head&& head, Tail&&... tail) { cerr << head; if (sizeof...(tail) != 0) cerr << " "; Debug(forward<Tail>(tail)...); }
template <class Type> void Debug(vector<Type> &vec) { for (auto& a : vec) { cerr << a; if (&a != &vec.back()) cerr << " "; } cerr << endl; }
template <class Type> void Debug(vector<vector<Type>> &df) { for (auto& vec : df) { Debug(vec); } }

static const int Lmax =  1'000;

int dp[Lmax][Lmax] = {0};

int main()
{
    Cin(int, q);
    while (q--)
    {
        Cin(string, X, Y);
        for (int i = 0, b = 0; i < len(Y); ++i)
        {
            b |= (Y[i] == X[0]);
            dp[i][0] = b;
        }
        for (int i = 0, b = 0; i < len(X); ++i)
        {
            b |= (X[i] == Y[0]);
            dp[0][i] = b;
        }

        range_for (i, 1, len(Y))
        {
            range_for (k, 1, len(X))
            {
                if (Y[i] == X[k])
                {
                    dp[i][k] = dp[i-1][k-1] + 1;
                }
                else
                {
                    dp[i][k] = max(dp[i-1][k], dp[i][k-1]);
                }
            }
        }

        Print(dp[len(Y) - 1][len(X) - 1]);
    }

    return 0;
}

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

int LCS(std::string str1, std::string str2, int i, int j){
  if(str1[i] == str2[j]){
    return 1;
  }
  else{
    return 0;
  }
}

int max(int a, int b, int c){
  int m = a;
  if(b > m){
    m = b;
  }
  if(c > m){
    m = c;
  }
  return m;
}

int main(){
  int q;
  std::cin >> q;
  //int ans[q];
  std::string str1, str2;
  for(int z=0; z<q; z++){
    std::cin >> str1 >> str2;
    int l1 = str1.size();
    int l2 = str2.size();
    int DP[l1+1][l2+1] = {};

    for(int i=1; i<=l1; i++){
      for(int j=1; j<=l2; j++){
	DP[i][j] = max(DP[i-1][j], DP[i][j-1], DP[i-1][j-1] + LCS(str1, str2, i-1, j-1));
      }
    }
    //ans[z] = DP[l1][l2];
    std::cout << DP[l1][l2] << std::endl;
  }

  /*for(int z=0; z<q; z++){
    std::cout << ans[z] << std::endl;
    }*/
  return 0;
}

C++: #include <iostream> 
#include <cstring> 
using namespace std;
int c[1001][1001];

int lcs(string x, string y)
{
    int maxl = 0;
    int m = x.length(), n = y.length();
 
    for (int i = 0; i <= m; i++) c[i][0] = 0;
    for (int j = 0; 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][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()
{
    string x,y;
    int q;
    cin>>q;
    while(q--)
    {
        cin>>x>>y;
        int ans = lcs(x, y);
        cout<<ans<<endl;
    }
    return 0;
}