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++: //#if 0
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//?????????????????§???????????§???AOJ?????????????????????Runtime Error??????????????????????????????
//??£????????¨??????????????????????????????????????????????????????Runtime Error???????????¨???????????????
//??§???????????????????????????????????§???
//#endif
#include<iostream>
#include<string>
#define lth 1000

using namespace std;

int main()
{
	int n, L[1010][1010], Lmax = 0, *save;
	string *Xi, *Yi;
	cin >> n;
	save = new int[n];
	if (n <= 20)
	{
		Xi = new string[lth];
		Yi = new string[lth];
	}
	else
	{
		Xi = new string[100];
		Yi = new string[100];
	}
	for (int k = 0; k < n; k++)
	{
		Lmax = 0;
		string X, Y;
		cin >> X >> Y;
		for (int i = 0; i <= X.length(); i++)
		{
			if (i != 0)
				Xi[i] = X.substr(0, i );
		}
		for (int i = 0; i <= Y.length(); i++)
		{
			if (i != 0)
				Yi[i] = Y.substr(0, i );
		}
		for (int i = 0; i <= X.length(); i++)
			for (int j = 0; j <= Y.length(); j++)
			{
				if (i == 0 || j == 0)
					L[i][j] = 0;
				else if (Xi[i][i - 1] == Yi[j][j - 1])
				{
					L[i][j] = L[i - 1][j - 1] + 1;
				}
				else
				{
					L[i][j] = (L[i][j - 1] > L[i - 1][j]?L[i][j - 1] : L[i - 1][j]);
				}
				if (Lmax < L[i][j]) Lmax = L[i][j];
			}
		save[k] = Lmax;
	}

	for (int i = 0; i < n; i++)
		cout << save[i] << endl;
}

C++: #include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
const int maxx = 1010;
int c[maxx][maxx];

int lcs(char s1[],char s2[]) {
	int m = strlen(s1), n = strlen(s2);
	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 (s1[i] == s2[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()
{
	char s1[maxx], s2[maxx];
	int t;
	scanf("%d", &t);
	for (int i = 0; i < t; i++) {
		cin >> s1 >> s2;
		printf("%d\n", lcs(s1,s2));
	}

	return 0;
}

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


int S[1001][1001];

void prep(string str1, string str2, int len)
{
	int a, b, i;
	S[0][0] = 0;
	for(i = 1; i <= len; i++){ S[0][i] = 0;  S[i][0] = 0; }
	for(a = 1; a <= len; a++){
		for(b = 1; b <= len; b++){
			if(str1[a - 1] == str2[b - 1]){ S[a][b] = 1; }else{ S[a][b] = 0; }
		}
	}
	return;
}

int main()
{
	int i, a, b, q, len;
	cin >> q;
	string str1, str2;

	for(i = 0; i < q; i++){
		cin >> str1 >> str2;
		len = str1.size();

		prep(str1, str2, len);

		for(a = 1; a <= len; a++){
			for(b = 1; b <= a; b++){
				if(S[b][a + 1 - b]){
					S[b][a + 1 - b] = S[b - 1][a - b] + 1; 
				}else{
					S[b][a + 1 - b] = max(S[b - 1][a + 1 - b], S[b][a - b]); }
			}
		}
		for(a = 2; a <= len; a++){
			for(b = a; b <= len; b++){
				if(S[b][len + a - b]){
					S[b][len + a - b] = S[b - 1][len + a - b - 1] + 1; 
				}else{
					S[b][len + a - b] = max(S[b - 1][len + a - b], S[b][len + a - b - 1]); }
			}
		}
		cout << S[len][len] << endl;
	}
	return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
#define INF 100000000
const int MOD = 1000000009;

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

// 最長共通部分列問題
// 入力
// S T

// dp[i + 1][j + 1] := Sのi文字目までと、Tのj文字目までのLCSの長さ
// 計算量 O(|S||T|)

int main(){

    //入力
    int n; cin >> n;
    for(int roop = 0; roop < n; roop++){
        string S, T; cin >> S >> T;
        vector<vector<int> > dp(S.size() + 1, vector<int> (T.size() + 1, 0));

        //dp初期条件
        dp[0][0] = 0;

        //dp
        for(int i = 0; i < S.size(); i++){
            for(int j = 0; j < T.size(); j++){
                if(S[i] == T[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]);
                dp[i + 1][j + 1] = max(dp[i + 1][j + 1], dp[i][j + 1]);
            }
        }

        cout << dp[S.size()][T.size()] << endl;
        
    }

    return 0;
}

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.clear();
    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;
}

C++: #include <cstdint>
#include <string>
#include <utility>

using namespace std;

#define MAX_LEN 1001
static size_t memo[MAX_LEN][MAX_LEN];

size_t lcs(string &a, string &b)
{
  for (uint32_t i = 0; i <= a.size(); i++) {
    memo[i][0] = 0;
  }

  for (uint32_t i = 0; i <= b.size(); i++) {
    memo[0][i] = 0;
  }

  for (uint32_t i = 1; i <= a.size(); i++) {
    for (uint32_t j = 1; j <= b.size(); j++) {
      if (a[i - 1] == b[j - 1]) {
        memo[i][j] = memo[i - 1][j - 1] + 1;
      } else {
        memo[i][j] = max(memo[i - 1][j], memo[i][j - 1]);
      }
    }
  }

  return memo[a.size()][b.size()];
}

#include <iostream>

int32_t main()
{
  uint32_t num;
  cin >> num;

  for (uint32_t i = 0; i < num; i++) {
    string a, b;
    cin >> a;
    cin >> b;
    cout << lcs(a, b) << endl;
  }

  return 0;
}