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 <bits/stdc++.h>
using namespace std;
int D; 
string S;

int N;
int solve(string s1, string s2){
    vector<vector<int> > dp(s1.size() + 1, vector<int>(s2.size() + 1, 0)); 
    for (int i = 1; i <= s1.size(); ++i){
        for (int j = 1; j <= s2.size(); ++j){
            if (s1[i - 1] == s2[j - 1]) {
                dp[i][j] = dp[i - 1][j - 1] + 1;
            }else{
                dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]);
            }
        }
    }
    return dp[s1.size()][s2.size()];
}
int main(){
    cin >> N;
    string temp1, temp2;
    for (int i = 0; i < N; ++i){
        cin >> temp1 >> temp2;
        cout << solve(temp1, temp2) << endl;
    }
}

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

int lcs(string X, string Y) {
  int dp[1000 + 1][1000 + 1];
  int max = 0;
  int m = X.size();
  int n = Y.size();
  X = ' ' + X;
  Y = ' ' + Y;

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

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

  for (int i = 1; i <= m; i++) {
    for (int j = 1; j <= n; j++) {
      if (X[i] == Y[j])
	dp[i][j] = dp[i-1][j - 1] + 1;
      else if (dp[i - 1][j] >= dp[i][j - 1])
	dp[i][j] = dp[i - 1][j];
      else
	dp[i][j] = dp[i][j - 1];

      if(max < dp[i][j])
	max = dp[i][j];
    }
  }

  return max;
}

int main() {
  int N = 0;
  cin >> N;

  string X, Y;
  for (int i = 0; i < N; i++) {
    cin >> X >> Y;

    cout << lcs(X, Y) << endl;
  }

  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 i,j;
  int maxl=0;
  X=' '+X;
  Y=' '+Y;
 
  for(i=1;i<=m;i++) c[i][0]=0;
  for(j=1;j<=n;j++) c[0]c[j]=0;

  for(i=1;i<=m;i++){
    for(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(i=0;i<n;i++){
    cin>>s1>>s2;
    cout<<lcs(s1,s2)<<enl;
  }
  return0;
}

C++: #include <iostream>
#include <string>
#include <vector>
#include <algorithm>
using namespace std;
int main()
{
    int n;
    cin >> n;
    {
        string t;
        getline(cin, t);
    }
    for(int i=0;i<n;i++) {
        string s1, s2;
        getline(cin, s1);
        getline(cin, s2);
        vector<int> v1(s2.size()+1, 0);
        vector<int> v2(s2.size()+1, 0);
        for(auto c1=s1.cbegin(); c1!=s1.cend(); ++c1) {
            int i = 1;
            for(auto c2=s2.cbegin(); c2!=s2.cend(); ++c2,i++) {
                auto m = max(v1[i], v2[i-1]);
                m = max(m, v1[i-1] + (*c1 == *c2 ? 1 : 0));
                v2[i] = m;
            }
            /*
            for(auto t=v1.begin();t!=v1.end();++t) {
                cout << *t << " ";
            }
            cout << endl;
            */
            swap(v1, v2);
        }
        cout << v1[s2.size()] << endl;
    }
}

C++: #include<iostream>
#include<string>
#include<vector>
#include<algorithm>
#include<cmath>

#define FOR(i,a,b) for(int i=(a);i<(b);++(i))
#define REP(i,n) FOR(i,0,n)

#define dump(x) cerr << #x << " = " <<(x)<<endl;
#define debug(x) cerr << #x << " = " <<(x) << "(L" << __LINE__ << ")" << __FILE__ << endl;

using namespace std;

int lis(string x, string y){
 vector<vector<int>> v(x.size()+1, vector<int>(y.size()+1));
  REP(i,(int)x.size()+1){
    REP(j,(int)y.size()+1){
      if(i==0 or j==0) v[i][j]=0;
      else if(x[i-1]==y[j-1]){ 
        v[i][j] = v[i-1][j-1]+1;
      }
      else{
        v[i][j]=max(v[i][j-1],v[i-1][j]);
      }
    }
  }
  return v[x.size()][y.size()];
}

int main(void){
  int i,j,q;
  cin >>q;
  string x;
  string y;
  REP(i,q) {
    cin >> x>> y;
    cout << lis(x,y)<< endl;

  }
  return 0;
}

C++: #include <iostream>
#include <stdio.h>
#include <string>
#include <algorithm>

using namespace std;

#define N 1000

int lcs(string X, string Y){
	int i,j,c[N+1][N+1],n,m;
	int maxl = 0;
	m = X.size();
	n = Y.size();

	X = ' ' + X;
	Y = ' ' + Y;

	for(i=1;i<=m;i++) c[i][0] = 0;
	for(j=0;j<=n;j++) c[0][j] = 0;

	for(i=1;i<=m;i++){
		for(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(void){

	string s1,s2;
	int i,n;

	scanf("%d",&n);
	for(i=0;i<n;i++){
		cin >> s1 >> s2;
		cout << lcs(s1,s2) << endl;
		//printf("%d\n",lcs(s1,s2));
	}
	return 0;
}

C++: #include <iostream>
#include <string>
#include <cstdio>
#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;
int ans = lcs(s1, s2);
printf("%d\n", ans);
}
return 0;
}

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

//#define FOR(i,a,b) for(int i=(a);i<(b);++i)
//#define REP(i,n)  FOR(i,0,n)

using namespace std;

static const int N = 10000;

// longest common sequence
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++)
    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 <iostream>
#include <string>
#include <cstring>
#define repi(i,a,b) for(int i=(a);i<(b);++i)
#define rep(i,a) repi(i,0,a)
#define clr(a,v) memset((a),(v),sizeof(a))

int q;
int dp[1000][1000];
std::string s, t;

int rec( int i, int j )
{
  int &ret = dp[i][j];

  if( ~ret )
    return ret;

  if( i == s.size() || j == t.size() )
    return 0;

  ret = 0;

  if( s[i] == t[j] )
    ret = std::max( ret, rec( i+1, j+1 )+1 );

  ret = std::max( ret, std::max( rec( i+1, j ), rec( i, j+1 ) ) );

  return ret;
}

int main()
{
  scanf( "%d", &q );
  while( q-- )
  {
    std::cin >> s >> t;

    clr( dp, -1 );

    std::cout << rec( 0, 0 ) << std::endl;
  }

  return 0;
}