Go: package main

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

var sc = bufio.NewScanner(os.Stdin)

func scanInt() int {
	num, _ := strconv.Atoi(scanString())
	return num
}

func scanString() string {
	sc.Scan()
	return sc.Text()
}

func init() {
	sc.Split(bufio.ScanWords)
}

func max(a, b int) int {
	if a > b {
		return a
	}
	return b
}

func lcs(a, b string) int {
	lenA := len(a)
	lenB := len(b)
	dp := make([][]int, lenA+1)
	for i := range dp {
		dp[i] = make([]int, lenB+1)
	}

	for i := 1; i <= lenA; i++ {
		for j := 1; j <= lenB; j++ {
			if a[i-1] == b[j-1] {
				dp[i][j] = dp[i-1][j-1] + 1
			} else {
				dp[i][j] = max(dp[i][j-1], dp[i-1][j])
			}
		}
	}
	return dp[lenA][lenB]
}

func main() {
	n := scanInt()
	w := bufio.NewWriter(os.Stdout)
	for i := 0; i < n; i++ {
		a := scanString()
		b := scanString()
		fmt.Fprintln(w, lcs(a, b))
	}
	w.Flush()
}

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

void solve(string, string);
int main(){
  int q; cin >> q;

  for(int i=0; i<q; i++){
    string s, t;  cin >> s >> t;
    solve(s, t);
  }

  return 0;
}

void solve(string s, string t){
  int m=s.length(), n=t.length();
  s = " " + s; t = " " + t;

  int dp[m+1][n+1];
  for(int i=0; i<=m; i++) dp[i][0]=0;
  for(int i=0; i<=n; i++) dp[0][i]=0;

  for(int i=1; i<=m; i++){
    for(int j=1; j<=n; j++){
      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]);
      }
    }
  }

  cout << dp[m][n] << endl;
}

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 maxl = 0;
	X = ' ' + X;
	Y = ' ' + Y;
	for (int i = 1; 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]);
			}
			maxl = max(maxl, c[i][j]);
		}
	}

	return maxl;
}

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<bits/stdc++.h>

#define rep(i,n) for(int i = 0; i < (n); i++)
#define rrep(i,n) for(int i = (n)-1; i >= 0; i--)
#define rep1(i,n) for(int i = 1; i <= (n); i++)
#define rrep1(i,n) for(int i = (n); i > 0; i--)

#define ll long long
#define pi pair<int, int>
#define pll pair<ll, ll>

#define MOD 1000000007
#define INF 1000000000000000LL

using namespace std;

#define MAXLEN 1001
int dp[MAXLEN][MAXLEN];

int main(){
  int n;cin>>n;
  rep(i, n){
    rep(i, MAXLEN)rep(j, MAXLEN)dp[i][j]=0;

    string l,r;cin>>l>>r;
    rep(x, l.size())rep(y, r.size()){
      if(l[x]==r[y]) dp[x+1][y+1] = dp[x][y]+1;
      else dp[x+1][y+1] = max(dp[x+1][y], dp[x][y+1]);

    // cout<<r[x]<<' '<<l[y]<<endl;
    // rep(x, l.size()+1){
    //   rep(y, r.size()+1)cout<<dp[x][y]<<' ';cout<<endl;
    // }
    // cout<<"#######"<<endl;

    }

    cout<<dp[l.size()][r.size()]<<endl;

  }
  return 0;
}

C++: #include <sstream>
#include <string>
#include <vector>
#include <map>
#include <algorithm>
#include <iostream>
#include <utility>
#include <set>
#include <cctype>
#include <queue>
#include <stack>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <climits>
using namespace std;
#define INF 100000000

typedef long long ll;
const int dx[] = {1, 0, -1, 0};
const int dy[] = {0, 1, 0, -1};

int dp[1010][1010];

int main(void) {
    int n;
    cin >> n;
    while (n--) {
        string a, b;
        cin >> a;
        cin >> b;
        for (int i = 0; i < 1010; i++) {
            for (int j = 0; j < 1010; j++) {
                dp[i][j] = 0;
            }
        }
        for (int i = 1; i <= a.size(); i++) {
            for (int j = 1; j <= b.size(); j++) {
                if (a[i-1] == b[j-1]) {
                    dp[i][j] = dp[i][j-1] + 1;
                } else {
                    dp[i][j] = max(dp[i-1][j], dp[i][j-1]);
                }
//                cout << dp[i][j] << "  ";
            }
//            cout << endl;
        }
        cout << dp[a.size()][b.size()] << endl;
    }
    return 0;
}

C++: 
#include<iostream>

int main(){
  int n;
  std::string x,y;
  std::cin>>n;
  int a[1000][1000];
  int b[n];

  for(int i=0;i<n;i++){
    std::cin>>x;
    std::cin>>y;
    for(int j=0;j<1000;j++){
      for(int k=0;k<1000;k++){
	a[j][k]=0;
      }
    }
    for(int j=0;j<x.size();j++){
      for(int k=0;k<y.size();k++){
	if(x[j]==y[k]){
	  a[j][k]=a[j-1][k-1]+1;
	}else{
	  if(a[j-1][k]>a[j][k-1]){
	    a[j][k]=a[j-1][k];
	  }else{
	    a[j][k]=a[j][k-1];
	  }
	}
      }
    }
    b[i]=a[x.size()-1][y.size()-1];
  }

  for(int i=0;i<n;i++){
  std::cout<<b[i]<<"\n";
  }

  return 0;
}

C++: #include <iostream>
#include <algorithm>
#include <vector>
#define rep(i, n) for(int i = 0; i < (int)(n); i++)
#define repR(i, n) for(int i = (n) - 1; i > -1; i--)
#define rep1(i, n) for(int i = 1; i < (int)(n + 1); i++)
#define rep1R(i, n) for(int i = (n); i > 0; i--)
using namespace std;

int q;
int dp[1010][1010];

void lcs(string& X, string& Y) {
  int m = X.size(), n = Y.size();
  rep1(i, m) dp[i][0] = 0;
  rep1(j, n) dp[0][j] = 0;
  rep1(i, m) rep1(j, n) {
    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]);
  }
}

int main() {
  cin >> q;
  rep(i, q) {
    string X, Y;
    cin >> X;
    cin >> Y;
    lcs(X, Y);
    int result = 0;
    rep1(i, X.size()) rep1(j, Y.size()) {
      result = max(result, dp[i][j]);
    }
    cout << result << endl;
  }
  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef pair<ll, ll> P;

#define pb push_back
#define rep(i, n) for(int i = 0; i < (n); i++)
#define FOR(i, a, n) for(int i = a; i < (n); i++)
#define mod (ll)(1e9+7)
#define int ll

__attribute__((constructor))
void initial() {
  cin.tie(0);
  ios::sync_with_stdio(false);
}

int lcs(string x, string y) {
  int c[1001][1001];
  int m = x.size(), n = y.size();
  int maxl = 0;
  x = ' ' + x, y = ' ' + y;
  for(int i = 0; i <= m; i++) c[i][0] = 0;
  for(int i = 1; i <= n; i++) c[0][i] = 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]);
      }
      maxl = max(maxl, c[i][j]);
    }
  }
  return maxl;
}

signed main() {
	ll n;
  string s1, s2;

  cin >> n;
  rep(i, n) {
    cin >> s1 >> s2;
    cout << lcs(s1, s2) << endl;
  }
}

C++: #include <iostream>
#include <vector>
using namespace  std;

void fnInput(vector<string>& rvsStrX, vector<string>& rvsStrY)
{
  int nMaxSiz;
  cin >> nMaxSiz;
  rvsStrX.resize(nMaxSiz);
  rvsStrY.resize(nMaxSiz);

  for (int i = 0; i < nMaxSiz; ++i)
  {
    cin >> rvsStrX[i] >> rvsStrY[i];
    rvsStrX[i] = ' ' + rvsStrX[i];
    rvsStrY[i] = ' ' + rvsStrY[i];
  }
}

int fnLngCmnSubseq(const vector<string>& cnrvsStrX, const vector<string>& cnrvsStrY)
{
  vector<vector<int>> vvnLcsDP;
  for (int i = 0; i < cnrvsStrX.size(); ++i)
  {
    const int nMAXNX = cnrvsStrX[i].size();
    const int nMAXNY = cnrvsStrY[i].size();

    vvnLcsDP.shrink_to_fit();
    vvnLcsDP.resize(nMAXNX, vector<int>(nMAXNY, 0));

    for (int nx = 1; nx < nMAXNX; ++nx)
      for (int ny = 1; ny < nMAXNY; ++ny)
        if (cnrvsStrX[i][nx] == cnrvsStrY[i][ny])
          vvnLcsDP[nx][ny] = vvnLcsDP[nx - 1][ny - 1] + 1;
        else
          vvnLcsDP[nx][ny] = max(vvnLcsDP[nx - 1][ny], vvnLcsDP[nx][ny - 1]);

    cout << vvnLcsDP[nMAXNX - 1][nMAXNY - 1] << endl;
  }
}

int main()
{
  cin.tie(0);
  ios::sync_with_stdio(false);
  vector<string> vsStrX, vsStrY;

  fnInput(vsStrX, vsStrY);
  fnLngCmnSubseq(vsStrX, vsStrY);
  return 0;
}