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] = dp[i-1][j-1]+1
				} else if S[i-1] != T[j-1] && dp[i-1][j] > dp[i][j-1] {
					dp[i][j] = dp[i-1][j]
				} else {
					dp[i][j] = dp[i][j-1]
				}
				// 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;

#pragma GCC optimize "O3"
#define rep(i,a,n) for(int i=a; i<n; i++)
typedef long long ll;
typedef pair<int,int> P;
const ll MOD = (int)1e9+7;
const ll INF = MOD*MOD;
const ll powll = 1LL<<1;


int main() {
    int t;
    cin >> t;
    rep(i,0,t){
        string s1,s2;
        cin >> s1 >> s2;
        int n1 = s1.size();
        int n2 = s2.size();
        int dp[n1+1][n2+1];
        rep(j,0,n1+1){
            rep(k,0,n2+1){
                dp[j][k] = 0;
            }
        }
        rep(j,0,n1){
            rep(k,0,n2){
                if(s1[j] == s2[k]){
                    dp[j+1][k+1] = max(dp[j+1][k], dp[j][k] + 1);
                }else{
                    dp[j+1][k+1] = max(dp[j+1][k], dp[j][k+1]);
                }
            }
        }
        // rep(j,0,n1+1){
        //     rep(k,0,n2+1){
        //         cout << dp[j][k] << " ";
        //     }
        //     cout << "\n";
        // }
        cout << dp[n1][n2] << "\n";
    }
}

C++: // http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=ALDS1_10_C
// Dynamic Programming - Longest Common Subsequence

#define SUBMIT

#include <utility>
#include <algorithm>
#include <iostream>
#include <iomanip>
#include <vector>
#include <limits>
#include <numeric>
#include <functional>
#include <set>
#include <cmath>
#include <cstring>
#include <climits>
#include <memory>

using namespace std;
using ui64 = unsigned long long;
using i64 = long long;

const ui64 MAX_N = 1000;
ui64 dp[MAX_N + 1][MAX_N + 1];

ui64 compute_lcs(string x, string y) {
    memset(dp, 0, sizeof(dp));

    for (int i = 0; i < x.length(); ++i) {
        for (int j = 0; j < y.length(); ++j) {
            if (x[i] == y[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]);
        }
    }

    return dp[x.length()][y.length()];
}

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

    string x, y;
    for (int i = 0; i < n; ++i) {
        cin >> x >> y;
        cout << compute_lcs(x, y) << endl;
    }

    return 0;
}

C++: #pragma GCC optimize ("O3")

#include <bits/stdc++.h>

using namespace std;

#ifdef LOCAL
#include <prettyprint.hpp>
#define debug(...)  cerr << "[" << #__VA_ARGS__ << "]: ", d_err(__VA_ARGS__);
#else
#define debug(...) 83;
#endif

void d_err() {
    cerr << endl;
}

template <typename H, typename... T>
void d_err(H h, T... t) {
    cerr << h << " ";
    d_err(t...);
}

template <typename T>
void print(T x) {
    cout << x << "\n";
}

#define ALL(x) (x).begin(), (x).end()
#define FOR(i, m, n) for (int i = (m); i < (n); ++i)
#define REVFOR(i, m, n) for (int i = (n - 1); i >= (m); --i)
#define REP(i, n) FOR(i, 0, n)
#define REVREP(i, n) REVFOR(i, 0, n)
#define fi first
#define se second
#define pb push_back
#define mp make_pair
#define eb emplace_back
#define bcnt __builtin_popcountll

typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef pair<ll,ll> Pll;
typedef pair<int,int> Pin;

ll INF = 1e16;
int inf = 1e9;
ll MOD = 1e9+7;


int main() {
    cin.tie(0);
    ios_base::sync_with_stdio(false);
    cout << fixed << setprecision(20);

    int q; cin >> q;

    REP(_, q) {
        string x, y; cin >> x >> y;

        vector<vi> dp(x.size() + 1, vi(y.size() + 1, 0));

        REP(i, x.size()) REP(j, y.size()) {
            dp[i + 1][j + 1] = max(dp[i + 1][j + 1], dp[i][j] + int(x[i] == y[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]);
        }

        print(dp[x.size()][y.size()]);
    }

}

C++: #include<bits/stdc++.h>
using namespace std;
using Int = long long;
template<typename T1,typename T2> inline void chmin(T1 &a,T2 b){if(a>b) a=b;}
template<typename T1,typename T2> inline void chmax(T1 &a,T2 b){if(a<b) a=b;}
//BEGIN CUT HERE
int lcs(string s,string t){
  int n=s.size(),m=t.size();
  s+='$';t+='%';
  vector<vector<int> > dp(n+2,vector<int>(m+2,-(n+m)));
  dp[0][0]=0;
  for(int i=0;i<=n;i++){
    for(int j=0;j<=m;j++){
      chmax(dp[i+1][j],dp[i][j]);
      chmax(dp[i][j+1],dp[i][j]);
      chmax(dp[i+1][j+1],dp[i][j]+(s[i]==t[j]));
    }
  }
  return dp[n][m];
}
//END CUT HERE

//INSERT ABOVE HERE
signed ALDS1_10_C(){
  cin.tie(0);
  ios::sync_with_stdio(0);
  int q;
  cin>>q;
  while(q--){
    string s,t;
    cin>>s>>t;
    cout<<lcs(s,t)<<"\n";
  }
  cout<<flush;
  return 0;
}
/*
  verified on 2019/04/07
  http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=ALDS1_10_C&lang=jp
*/

signed main(){
  ALDS1_10_C();
  return 0;
}

C++: #include <bits/stdc++.h>
#define rep(i,a,b) for(int i=int(a);i<int(b);++i)
#define SIZE 1005
#define INF 1000000005LL
//#define INF 1e18
#define MOD 1000000007

using namespace std;
typedef long long int ll;
typedef pair <int,int> P;

int dp[SIZE][SIZE];

void solve(){
  int n,m;
  string X,Y;
  cin >> X >> Y;
  n = X.size();
  m = Y.size();
  fill(dp[0],dp[0]+SIZE,0);
  rep(i,0,n) rep(j,0,m){
    int a=0,b=0,c=0;
    if(i>0)a = dp[i-1][j];
    if(j>0)b = dp[i][j-1];
    if(i>0 && j>0)c = dp[i-1][j-1];
    dp[i][j] = max({a,b,c+(X[i]==Y[j]?1:0)});
  }
  cout << dp[n-1][m-1] << endl;
}

int main(){

  int q;
  cin >> q;
  rep(i,0,q){
    solve();
  }

  return 0;
}

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

int dp[1001][1001];
int q;

void solve(){
  char x[1001],y[1001];
  scanf("%s %s",x,y);
  int lx = strlen(x);
  int ly = strlen(y);
  for(int i=0;i<=lx;i++){
    for(int j=0;j<=ly;j++){
      if(i==0||j==0) dp[i][j] = 0;
      else if(x[i]==y[j]) dp[i][j] = dp[i-1][j-1]+1;
      else dp[i][j] = max(dp[i][j-1],dp[i-1][j]);
    }
  }
  printf("%d\n",dp[lx][ly]);
  return;
}


int main(){
  scanf("%d",&q);
  for(int i=0;i<q;i++) solve();
  return 0;
}