Go: package main

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

// define
var (
	sc = bufio.NewScanner(os.Stdin)
)

func bordersInt(in_map [][]int, invalid int) [][]int{
	H, W := len(in_map), len(in_map[0])
	out_map := make([][]int, H+2)
	for h:=0; h<H+2; h++ {
		out_map[h] = make([]int, W+2)
		for w:=0; w<W+2; w++ {
			out_map[h][w] = invalid
		}
	}
	for h:=0; h<H; h++{
		for w:=0; w<W; w++{
			out_map[h+1][w+1] = in_map[h][w] 
		}
	}
	return out_map
}

func bordersString(in_map [][]string, invalid string) [][]string{
	H, W := len(in_map), len(in_map[0])
	out_map := make([][]string, H+2)
	for h:=0; h<H+2; h++ {
		out_map[h] = make([]string, W+2)
		for w:=0; w<W+2; w++ {
			out_map[h][w] = invalid
		}
	}
	for h:=0; h<H; h++{
		for w:=0; w<W; w++{
			out_map[h+1][w+1] = in_map[h][w] 
		}
	}
	return out_map
}

func scanIntLine(len int) []int{
	arr := make([]int, len)
	for i:=0; i<len; i++{
		sc.Scan()
		tmp, err := strconv.Atoi(sc.Text())
		if err == nil{
			arr[i] = tmp
		}
	}
	return arr
}

func scanStringLine(len int) []string{
	arr := make([]string, len)
	for i:=0; i<len; i++{
		sc.Scan()
		arr[i] = sc.Text()
	}
	return arr
}

func scanIntSplit(len int) []int{
	arr := make([]int, len)
	sc.Scan()
	for i, v := range strings.Split(sc.Text(), " "){
		tmp, err := strconv.Atoi(v)
		if err == nil{
			arr[i] = tmp
		}
	}
	return arr
}

func maxInt(args... int) int{
	sort.Ints(args)
	return args[len(args)-1]
}

func main(){
	buf := make([]byte, 0)
    sc.Buffer(buf, 1000000009)
	var n int 
	fmt.Scan(&n)
	dp := make([][]int, 1003)
	for i:=0; i<1003; i++ {
		dp[i] = make([]int, 1003)
	}
	input_lines := scanStringLine(2*n)
	for i:=0; i<n; i++ {
		S, T := input_lines[2*i], input_lines[2*i+1]
		lenS, lenT := len(S), len(T)
		for i:=1; i<lenS+1; i++ {
			for j:=1; j<lenT+1; j++ {
				if S[i-1] == T[j-1] {
					dp[i][j] = maxInt(dp[i-1][j-1]+1, dp[i-1][j], dp[i][j-1])
				} else {
					dp[i][j] = maxInt(dp[i-1][j], dp[i][j-1])
				}
			}
		}
		fmt.Println(dp[lenS][lenT])
	}
}

C++: #include "bits/stdc++.h"
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
#define rep(i,n) for(ll i=0;i<(ll)(n);i++)
#define all(a)  (a).begin(),(a).end()
#define pb push_back
#define INF 99999999

#define MAX_S 200
#define MAX_T 200

template<typename T> int lcs(T s,T t){
    int lens=s.size();
    int lent=t.size();
    int dp[MAX_S+1][MAX_T+1]={};

    rep(i,lens){
        rep(j,lent){
            if(s[i]==t[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]);
        }
    }
    return dp[lens][lent];
}

int main(){
    int n;
    cin>>n;
    rep(i,n){
        string s,t;
        cin>>s>>t;
        cout<<lcs(s,t)<<endl;
    }
}

C++: #include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
const int maxx = 1010;
int c[maxx][maxx];

int lcs(char s1[],char s2[]) {
	int m = strlen(s1), n = strlen(s2);
	for (int i = 1; i <= m; i++)
		c[i][0] = 0;
	for (int i = 1; i <= n; i++)
		c[0][i] = 0;

	for (int i = 0; i < m; i++) {
		for (int j = 0; j < n; j++) {
			if (s1[i] == s2[j])
				c[i+1][j+1] = c[i][j] + 1;
			else
				c[i+1][j+1] = max(c[i][j+1], c[i + 1][j]);
		}
	}
	return c[m][n];
}
int main()
{
	char s1[maxx], s2[maxx];
	int t;
	scanf("%d", &t);
	for (int i = 0; i < t; i++) {
		scanf("%s %s", s1, s2);
		printf("%d\n",lcs(s1,s2));
	}

	return 0;
}

C++: #include<iostream>
#include<array>
#define REP(i,n) for(int i=0;i<(int)(n);i++)
using namespace std;
const int MAX_V = 1001;
array<array<int, MAX_V>,MAX_V> ary;
string strx,stry;
int minimum(int x,int y){
  int res=strx[x]==stry[y]?ary[x-1][y-1]+1:ary[x-1][y-1];
  if(res<ary[x][y-1]) res=ary[x][y-1];
  if(res<ary[x-1][y]) res=ary[x-1][y];
  return res;
}

int main(){
  int n; cin>>n;
  REP(i,n){
    cin>>strx>>stry;
    int sizex=strx.size(),sizey=stry.size();
    REP(j,sizex)
      REP(k,sizey)
        ary[j+1][k+1]=minimum(j+1,k+1);
    cout<<ary[strx.size()][stry.size()]<<endl;
  }
}

C++: #include <bits/stdc++.h>
#define ll long long
#define INF 1000000005
#define MOD 1000000007
#define EPS 1e-10
#define rep(i,n) for(int i=0;i<(int)(n);++i)
#define rrep(i,n) for(int i=(int)(n)-1;i>=0;--i)
#define srep(i,s,t) for(int i=(int)(s);i<(int)(t);++i)
#define each(a,b) for(auto& (a): (b))
#define all(v) (v).begin(),(v).end()
#define len(v) (int)(v).size()
#define zip(v) sort(all(v)),v.erase(unique(all(v)),v.end())
#define cmx(x,y) x=max(x,y)
#define cmn(x,y) x=min(x,y)
#define fi first
#define se second
#define pb push_back
#define show(x) cout<<#x<<" = "<<(x)<<endl
#define spair(p) cout<<#p<<": "<<p.fi<<" "<<p.se<<endl
#define sar(a,n) cout<<#a<<":";rep(pachico,n)cout<<" "<<a[pachico];cout<<endl
#define svec(v) cout<<#v<<":";rep(pachico,v.size())cout<<" "<<v[pachico];cout<<endl
#define svecp(v) cout<<#v<<":";each(pachico,v)cout<<" {"<<pachico.first<<":"<<pachico.second<<"}";cout<<endl
#define sset(s) cout<<#s<<":";each(pachico,s)cout<<" "<<pachico;cout<<endl
#define smap(m) cout<<#m<<":";each(pachico,m)cout<<" {"<<pachico.first<<":"<<pachico.second<<"}";cout<<endl

using namespace std;

typedef pair<int,int> P;
typedef pair<ll,ll> pll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<double> vd;
typedef vector<P> vp;
typedef vector<string> vs;

const int MAX_N = 100005;

const int MAX_SIZE = 26;

int LCS(const string& a, const string& b){
    int n = (int)a.size(), m = (int)b.size();
    vector<int> x(n), y(m);
    rep(i,n){
        x[i] = a[i]-'a';
    }
    rep(i,m){
        y[i] = b[i]-'a';
    }
    vector<vector<int> > vec(MAX_SIZE);
    for(int j = m-1; j >= 0; --j){
        vec[y[j]].push_back(j);
    }
    vector<int> xs(n+1, INF);
    xs[0] = -1;
    vector<P> nx(n+1,P(-INF,-INF));
    rep(i,n){
        vector<int>& ys = vec[x[i]];
        rep(j,(int)ys.size()){
            int k = lower_bound(xs.begin(),xs.end(),ys[j]) - xs.begin();
            xs[k] = ys[j];
            nx[k] = P(y[ys[j]], k-1);
        }
    }
    return lower_bound(xs.begin(),xs.end(),INF-1) - xs.begin() - 1;
}


int main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    int q;
    cin >> q;
    rep(i,q){
        string a,b;
        cin >> a >> b;
        cout << LCS(a,b) << "\n";
    }
    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
const long long INF = 123456789;
const long long MOD = 1000000007;
const long double PI = 3.1415926;
#define FOR(i, r, n) for (ll i = (ll)(r); i < (ll)(n); i++)
#define RFOR(i, r, n) for (ll i = (ll)(n - 1); i >= r; i--)
#define REP(i, n) FOR(i, 0, n)
#define RREP(i, n) RFOR(i, 0, n)
#define ALL(x) x.begin(), x.end()
#define RALL(x) x.rbegin(), x.rend()
typedef long long int ll;
typedef vector<ll> vi;
typedef vector<pair<ll, ll> > vp;
typedef vector<string> vs;
typedef vector<char> vc;
typedef list<ll> lst;

ll n, m, k, ans = 0, sum = 0, cnt = 0;
string s;
char c;

#define Endl endl

/*--------------------template--------------------*/

ll dp[1006][1006] = { 0 };

int main()
{
    cin >> n;
    ll ma = 0;
    REP(i, n)
    {
        string t;
        cin >> s >> t;
        ma = 0;
        s = ' ' + s; //????????????????????????
        t = ' ' + t;
        FOR(i, 1, s.size())
        {
            dp[i][0] = 0;
        }
        FOR(i, 1, t.size())
        {
            dp[0][i] = 0;
        }
        FOR(i, 1, s.size())
        {
            FOR(j, 1, t.size())
            {
                if (s[i] == t[j]) {
                    dp[i][j] = dp[i - 1][j - 1] + 1;
                } else {
                    dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]);
                }
                ma = max(ma, dp[i][j]);
            }
        }
        cout << ma << Endl;
    }
}