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;
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define rep(i,n)   FOR(i,0,n)
#define pb emplace_back
typedef long long ll;
typedef pair<int,int> pint;

int dp[1001][1001];
int main(){
    int n;
    string s,t;
    cin>>n;
    rep(i,n){
        cin>>s>>t;
        memset(dp,0,sizeof(dp));
        int ss=s.size(),st=t.size();
        rep(i,ss){
            rep(j,st){
                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]);
                }
            }
        }
        cout<<dp[ss][st]<<endl;
    }
    return 0;
}

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

int dp[150+1][150+1];

int lcsSub(std::string X, std::string Y, int i, int j){
	if (i==-1 || j==-1){
		return 0;
	}
	else{
		if(X[i]==Y[j]){
			if (dp[i][j] < 0){
				dp[i][j] = lcsSub(X, Y, i-1, j-1);
			}
			return dp[i][j]+1;
		}
		else{
			int up, left;
			if (dp[i+1][j] < 0){
				dp[i+1][j] = lcsSub(X, Y, i, j-1);
			}
			left = dp[i+1][j];
			if (dp[i][j] < 0){
				dp[i][j+1] = lcsSub(X, Y, i-1, j);
			}
			up = dp[i][j+1];
			
			return std::max(up, left);
		}
	}
}

int lcs(std::string X, std::string Y){
	int m,n,i,j;
	m = X.length();
	n = Y.length();
	for(i=0;i<m+1;i++){
		for(j=0;j<n+1;j++){
			dp[i][j] = -1;
		}
	}
	return lcsSub(X, Y, m-1, n-1);
}
int main(void){
	int i,q,n,m;
	std::string str1, str2;
	std::cin >> q;
	for (i=0;i<q;i++){
		std::cin >> str1;
		std::cin >> str2;
		std::cout << lcs(str1, str2) << std::endl;
	}
	return 0;
}

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

int main(){
    int q;
    for(int i = 0; i < q; i++){
        string S1, S2;
        cin >> S1 >> S2;
        const int m = S1.size();
        const int n = S2.size();
        int dp[m][n] = {0};
        for(int j = 0; j < m; j++){
            for(int k = 0; k < n; k++){
                if(j == 0 && k == 0);
                else if(j == 0) dp[j][k] = dp[j][k-1];
                else if(k == 0) dp[j][k] = dp[j-1][k];
                else{
                    dp[j][k] = max(dp[j-1][k],dp[j][k-1]);
                }
                if(S1[j] == S2[k]) dp[j][k]++;
            }
        }
        cout << dp[m-1][n-1] << endl;
    }
}

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

#define MAX_SIZE 1010

int lcm(string X, string Y) {
    int c[MAX_SIZE][MAX_SIZE];
    int m = X.size(), n = Y.size();
    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]);
        }
    }

    return c[m][n];
}

int main() {
    int q;
    cin >> q;
    string X, Y;
    for (int i = 0; i < q; i++) {
        cin >> X >> Y;
        cout << lcm(X, Y) << endl;
    }
    return 0;
}

C++: #include<iostream>
#include<cstdio>
#include<algorithm>
#include<string>
#include<cstring>
#define maxn 1005
using namespace std;

int dp[maxn][maxn];
int len1, len2;
string s1, s2;

int lcs()
{
	memset(dp, 0, sizeof(dp));
	for(int i=1;i<=len1;i++)
		for (int j = 1; j <= len2; j++)
		{
			if (s1[i] == s2[j]) {
				dp[i][j] = dp[i - 1][j - 1] + 1;
			}
			else
			{
				dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]);
			}
		}
	return dp[len1][len2];
}

int main()
{
	int n;
	cin >> n;
	while (n--)
	{
		cin >> s1 >> s2;
		len1 = s1.size(), len2 = s2.size();
		s1 = ' ' + s1;
		s2 = ' ' + s2;
		cout << lcs() << endl;
	}
	return 0;
}

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

#define FOR( i, m, n )  for( int (i) = (m); (i) < (n); (i)++ )
#define REP( i, n )     FOR( i, 0, n )
#define ALL( a )        (a).begin(), (a).end()             

int	dp[1001][1001] = {};

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

	int maxl;

	string s1, s2;
	REP( i, n ) {
		cin >> s1 >> s2;
		maxl = 0;
		memset( dp, 0, sizeof( int ) );
		FOR( j, 1, s1.size() + 1 ) {
			FOR( k, 1, s2.size() + 1 ) {
				if( s1[j] == s2[k] ) {
					dp[j][k] = dp[j - 1][k - 1] + 1;
				} else {
					dp[j][k] = max( dp[j - 1][k], dp[j][k - 1] );
				}
				maxl = max( dp[j][k], maxl );
			}
		}

		cout << maxl << endl;
	}
}

C++: #include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cassert>
#include <string>
#include <cstring>
#include <vector>
#include <list>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <algorithm>

using namespace std;

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

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

// ---------------------
#define INF 922337203685477580
typedef long long ll;

int dp[1000][1000];

int main() {
  int q;
  cin >> q;
  REP(loop, q) {
    char S[1000], T[1000];
    cin >> S >> T;

    dp[0][0] = 0;
    for (int i = 0; i < strlen(S); i++) {
      for (int j = 0; j < strlen(T); j++) {
        if (S[i] == T[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]);
        }
      }
    }
    cout << dp[strlen(S) - 1][strlen(T) - 1] << 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 maxl = 0;
    
    X = ' ' + X; //insert a space to X[0]
    Y = ' ' + Y; //insert a space to Y[0]
    
    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]);
            }
            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"cstring"
using namespace std;

int c[1001][1001];
void lcs(char*a,char*b)
{
	int m = strlen(a);
	int n = strlen(b);
	int i, j;
	for(i=0;i<1001;++i)
	{
		c[0][i] = 0;
		c[i][0] = 0;
	}
	for (i = 1; i <= m; ++i)
		for (j = 1; j <= n; ++j)
			if (a[i-1] == b[j-1])c[i][j] = c[i - 1][j - 1] + 1;
			else c[i][j] = c[i][j - 1] > c[i - 1][j] ? c[i][j - 1] : c[i - 1][j];
	cout<<c[m][n]<<endl;
}
int main()
{
	int n,i;
	cin >> n;
	cin.get();
	char** a = new char* [2 * n];
	for (i = 0; i < 2 * n; ++i)
	{
		a[i] = new char[1001];
		cin.getline(a[i], 1001);
	}
	for (i = 0; i < 2 * n; i += 2)
		lcs(a[i], a[i + 1]);
	return 0;
}