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 <iostream>
#include <string>
using namespace std;

void solve(string X, string Y);

int main(int argc, char const *argv[]) {
	int N;
	cin >> N;


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

	return 0;
}

void solve(string X, string Y) {
	int **c = new int*[1000 + 1];
	for (int i = 0; i < 1000 + 1; i++)
		c[i] = new int[1000 + 1];

	int max = 0;
	int m = X.size();
	int n  = Y.size();
	X = ' ' + X;
	Y = ' ' + Y;

	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 = 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 if (c[i - 1][j] >= c[i][j - 1])
	      c[i][j] = c[i - 1][j];
	    else
	      c[i][j] = c[i][j - 1];

	    max = (max < c[i][j]) ? c[i][j] : max;
	  }
	}

	cout << max << endl;

	for (int i = 0; i < 1000 + 1; i++)
		delete c[i];

	delete[] c;
}

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

static const int N = 1000;

int longestCommonSubsequence(string X, stringY)  {
  int c[N + 1][N + 1];
  int m = X.size();
  int n = Y.size();
  intmax1 = 0;
  X = ' ' + X;
  Y = ' ' + Y;
  for (int i = 0; i <= m; i++) 
    c[i][0] = 0;
  for (int j = 1; j <= n; j++)
    s[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]);
      }
      max1 = max(max1, c[i][j]);
    }
  }
  return max1;
}
 
int main()  {
  string s1, s2;
  int n;
  cin >> n;
  for (int i = 0; i < n; i++)  {
    cin >> s1 >> s2;
  cout << longestCommonSubsequence(s1, s2) << endl;
  }
  return ;
}

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; // X[0]に空白を挿入
    Y = ' ' + Y;
    for (int i=0; i<m; i++) C[i][0] = 0;
    for (int j=0; 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][j-1], C[i-1][j]);
            }
            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"

using namespace std;

using ll = long long;
using ld = long double;
using P = pair<string, int>;
constexpr ld EPS = 1e-12;
constexpr int INF = numeric_limits<int>::max() / 2;
constexpr int MOD = 1e9 + 7;

template <typename T>
void printv(const vector<T> &v)
{
    int sz = v.size();
    for (int i = 0; i < sz; i++)
    {
        cout << v[i] << " \n"[i == sz - 1];
    }
}

int main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);

    int q;
    cin >> q;
    while (q--)
    {
        string s, t;
        cin >> s >> t;
        int n = s.length(), m = t.length();
        s = "$" + s;
        t = "$" + t;
        vector<vector<int>> dp(n + 1, vector<int>(m + 1, 0));
        for (int i = 1; i <= n; i++)
        {
            for (int j = 1; j <= m; 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[n][m] << endl;
    }
}

C++: #include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<n;i++)
int main(){
    int n;
    cin >> n;
    rep(i,n){
        string a,b;
        cin >> a >> b;
        int n1 = a.size();
        int n2 = b.size();
        int dp[n1+1][n2+1];
        rep(i,n1+1)rep(j,n2+1)dp[i][j] = 0;
        rep(i,n1)rep(j,n2){
            if(a[i] == b[j]&&dp[i+1][j] == dp[i][j+1]&&dp[i][j] ==dp[i+1][j])dp[i+1][j+1] = dp[i+1][j]+1;
            else dp[i+1][j+1] = max(dp[i+1][j],dp[i][j+1]);
        }
        cout << dp[n1][n2] << endl;
    }
    return 0;
}

C++: #include <iostream>
#include <string>
#include <cstdio>
#include <vector>
#include <queue>
#include <map>
using namespace std;

int charCode(char charactor) {
	if(charactor>='a' && charactor <= 'z') return (int)(charactor-'a');
	else return (int)(charactor-'A'+26);
}

bool findSubStr(string& shortword, vector<vector<int> >& charMap) {
	int i,j=0;
	for(i=0; i<(int)shortword.size(); ++i) {
		if(charMap[charCode(shortword[i])].empty()) return false;
		auto itr=charMap[charCode(shortword[i])].begin();
		while(itr!=charMap[charCode(shortword[i])].end()) {
			if(*itr<j) {
				++itr;
			} else {
				break;
			}
		}
		if(itr==charMap[charCode(shortword[i])].end()) return false;
		j=1+*itr;
	}
	return true;
}

int longestSQ(string& shortword, string& longword) {
	int i,j;
	string tempstr,prestr;
	vector<vector<int> > charMap(52);
	queue<string> targetword;
	map<string,bool> inqueue;
	for(i=0; i<(int)longword.size(); ++i) {
		charMap[charCode(longword[i])].push_back(i);
	}
	targetword.push(shortword);
	while(!targetword.empty()) {
		tempstr=targetword.front();
		if(findSubStr(tempstr,charMap)) return (int)tempstr.size();
		j=(int)tempstr.size();
		for(i=0; i<j; ++i) {
				tempstr=targetword.front();
				if(i==0 || tempstr[i]!=tempstr[i-1]) {
					tempstr.erase(tempstr.begin()+i);
					if(inqueue.find(tempstr)==inqueue.end()) {
						targetword.push(tempstr);
						inqueue[tempstr]=true;
					}
				}
		}
		targetword.pop();
	}
	return 0;
}

int main() {
	int i,q;
	cin >> q;
	string wordA,wordB;
	for(i=0; i<q; ++i) {
		cin >> wordA >> wordB;
		if(wordA.size()<wordB.size()) {
			printf("%d\n",longestSQ(wordA,wordB));
		} else {
			printf("%d\n",longestSQ(wordB,wordA));
		}
	}
	return 0;
}