Go: package main

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

func max(x, y int) int {
	if x < y {
		return y
	} else {
		return x
	}
}

func main() {
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Scan()
	n, _ := strconv.Atoi(scanner.Text())
	for i := 0; i < n; i++ {
		scanner.Scan()
		s1 := scanner.Text()
		scanner.Scan()
		s2 := scanner.Text()
		s1, s2 = " " + s1 , " " + s2
		c := make([][]int, len(s1))
		for i := range c {
			c[i] = make([]int, len(s2))
		}

		LCS := 0

		for i := 1; i < len(s1); i++ {
			for j := 1; j < len(s2); j++ {
				if s1[i] == s2[j] {
					c[i][j] = c[i-1][j-1] + 1
				} else {
					c[i][j] = max(c[i-1][j], c[i][j-1])
				}
				LCS = max(LCS, c[i][j])
			}
		}
		fmt.Println(LCS)
	}
}

C++: #include <stdio.h>
#include <iostream>
#include <algorithm>
??
using namespace std;
??
short checkTable[1001][1001];
??
int tmp_max=0;
??
??
void calc(int index,char pattern[],char to_search[],int to_search_length){
??
????????for(int i=to_search_length-1;i>=0;i--){
????????????????if(to_search[i]==pattern[index]){
????????????????????????checkTable[index][i]=1;
????????????????????????if(pattern[index+1]!='\0' && i < to_search_length-1){
????????????????????????????????checkTable[index][i] = checkTable[index+1][i+1] + checkTable[index][i];
????????????????????????}
????????????????}else{
????????????????????????if(i != to_search_length-1){
????????????????????????????????if(pattern[index+1] != '\0'){
????????????????????????????????????????checkTable[index][i]=(checkTable[index+1][i]>checkTable[index][i+1])
?????????????????????????????????????????????????????????checkTable[index+1][i]:checkTable[index][i+1];
??
????????????????????????????????}else{
????????????????????????????????????????checkTable[index][i]=(checkTable[index][i+1]>0)?checkTable[index][i+1]:0;
????????????????????????????????}
????????????????????????}else{
????????????????????????????????if(pattern[index+1] != '\0'){
????????????????????????????????????????checkTable[index][i]=(checkTable[index+1][i]>0)?checkTable[index+1][i]:0;
????????????????????????????????}else{
????????????????????????????????????????checkTable[index][i] = 0;
????????????????????????????????}
????????????????????????}
????????????????}
????????????????tmp_max = (tmp_max >= checkTable[index][i])?tmp_max:checkTable[index][i];
????????}
}
??
int main(){
??
????????int q,left_length,right_length;
????????char left[1001],right[1001];
??
????????scanf("%d",&q);
??
????????for(int i=0;i<q;i++){
????????????????left_length=0;
????????????????right_length=0;
????????????????scanf("%s %s",left,right);
????????????????for(int k=0;left[k]!='\0';k++)left_length++;
????????????????for(int k=0;right[k]!='\0';k++)right_length++;
??
????????????????if(right_length>=left_length){
??
????????????????????????for(int k=left_length-1;k>=0;k--)calc(k,left,right,right_length);
????????????????}else{
??
????????????????????????for(int k=right_length-1;k>=0;k--)calc(k,right,left,left_length);
????????????????}
????????????????printf("%d\n",tmp_max);
????????????????tmp_max=0;
????????}
??
????????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 res = 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]);

			}
			res = max(res, c[i][j]);
		}
	}
	return res;
}

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 <vector>
#include <algorithm>
#include <numeric>
#define FOR(i,b,e) for(int i=b;i<e;i++)
#define REP(i,n) FOR(i,0,n)
using namespace std;

string s1, s2;

int lcs(int n1, int n2) {
  if (n1 < 0 || n2 < 0) return 0;
  
  if (s1[n1] == s2[n2]) return 1 + lcs(n1 - 1, n2 - 1);
  else return max(lcs(n1, n2 - 1), lcs(n1 - 1, n2));
}

int main() {
	cin.tie(0);
 	ios::sync_with_stdio(false);

  int q; cin >> q;
  REP(i, q) {
    cin >> s1;
    cin >> s2;

    cout << lcs(s1.length() - 1, s2.length() - 1) << endl;
  }
}

C++: // https://ei1333.github.io/luzhiled/
// http://beet-aizu.hatenablog.com/entry/2017/01/04/113233
// http://www.prefield.com/algorithm/
#include <bits/stdc++.h>
constexpr char bn = '\n';
using namespace std;
using ll = long long;
using ld = long double;
using vl = vector<ll>;
using vd = vector<ld>;
using vs = vector<string>;
using vb = vector<bool>;
using vvl = vector<vector<ll>>;
using vvd = vector<vector<ld>>;
using vvs = vector<vector<string>>;
using vvb = vector<vector<bool>>;
#define pb push_back
#define eb emplace_back
#define fi first
#define se second
template<class T> using vc = vector<T>;
template<class T> using vvc = vector<vector<T>>;
using Graph = vector<vector<ll>>;
const ll INF = 1LL << 60;
void init() {cin.tie(0);ios::sync_with_stdio(false);cout << fixed << setprecision(15);}
const ll tl= 1000000007;
#define REP(i, n) for (ll i = 0; i < n; i++)
#define REREP(i, n) for (ll i = n; i >= 0; i--)
#define FOR(i, a, n) for (ll i = a; i < n; i++)
#define REFOR(i, n, a) for (ll i = n; i >= a; i--)
#define UNIQUE(v) v.erase( unique(v.begin(), v.end()), v.end() ) //被り削除
#define debug cout << "line : " << __LINE__ << " debug" << endl;
#define ini(...) int __VA_ARGS__; in(__VA_ARGS__)
#define inl(...) long long __VA_ARGS__; in(__VA_ARGS__)
#define ind(...) long double __VA_ARGS__; in(__VA_ARGS__)
#define ins(...) string __VA_ARGS__; in(__VA_ARGS__)
#define inc(...) char __VA_ARGS__; in(__VA_ARGS__)
void in(){} template <typename T,class... U> void in(T &t,U &...u){ cin >> t; in(u...);}
void out(){cout << endl;} template <typename T,class... U> void out(const T &t,const U &...u){ cout << t; if(sizeof...(u)) cout << " "; out(u...);}
template<typename T>void die(T x){out(x); exit(0);}
#define in1(A) REP(i,A.size()) in(A[i]);
#define in2(A,B) REP(i,A.size()) in(A[i],B[i]);
#define in3(s,t,u) REP(i,sz(s)){in(s[i] , t[i] , u[i]);}
#define in4(s,t,u,v) REP(i,sz(s)){in(s[i] , t[i] , u[i] , v[i]);}
#define each(x,v) for(auto& x : v)
#define all(v) (v).begin(),(v).end()
#define sz(v) ((int)(v).size())
struct Point{ ld x,y; };
ld dist(Point a, Point b){return sqrt(abs(a.x-b.x)*abs(a.x-b.x)+abs(a.y-b.y)*abs(a.y-b.y));} // ２点間の距離 
ll gcd(ll a, ll b) { return b != 0 ? gcd(b, a % b) : a; }
ll lcm(ll a,ll b){ return a / gcd(a,b) * b;} 
ll fact(ll n){ if(n < 2) return 1; return (n * fact(n-1))%tl; } //階乗
inline ll updiv(ll a,ll b){ return (a + b - 1) / b; } //切り上げ
template<typename T,typename U>ll ceil(T a,U b){return (a + b - 1) / b;}
template <class A, class B> inline bool chmax(A &a, const B &b) { return b > a && (a = b, true); }
template <class A, class B> inline bool chmin(A &a, const B &b) { return b < a && (a = b, true); }
//-------------------------------------------------------------------------------------------------
ll lcs(string x, string y){
    ll r= x.size(),c= y.size();
    vvl A(r, vl(c,0));
    REP(i,r){ // xをiもじめまで見る
        REP(j,c){ //yをj
            // 最初やること xとyそれぞれ1文字目が含まれているか
            // 含まれていたらそれ以降1
            if(!(i*j)){
                if(i) A[i][0]= A[i-1][0];
                if(j) A[0][j]= A[0][j-1];
                if(x[i]==y[j]) A[i][j]=1;
            }else{
                if(x[i]!=y[j]){
                    //間違いなら左か上から大きい方
                    A[i][j]= max(A[i-1][j],A[i][j-1]);
                }else{
                    //合っていたなら左上+1
                    // 左や上から取ることはできない(すでにその文字が使われているため)
                    A[i][j]= A[i-1][j-1]+1;
                }
            }
        }
    }

    return A[r-1][c-1];
}
int main(){
    init();
    inl(n); 
    vl ans;
    while(n--){
        ins(x,y);
        ans.pb(lcs(x,y));
    }
    each(x,ans) out(x);
}