Go: package main

/*
最長共通部分列
*/

import (
	"bufio"
	"bytes"
	"fmt"
	"log"
	"os"
	"strconv"
	"strings"
)

func larger(l, r int) int {
	if l > r {
		return l
	}
	return r
}

var memo [1001][1001]int

func countLCS(x, y string) int {
	x = " " + x
	y = " " + y
	max := 0
	for xi := 1; xi < len(x); xi++ {
		for yi := 1; yi < len(y); yi++ {
			if x[xi] == y[yi] {
				memo[xi][yi] = memo[xi-1][yi-1] + 1
			} else {
				memo[xi][yi] = larger(memo[xi-1][yi], memo[xi][yi-1])
			}
			max = larger(max, memo[xi][yi])
		}
	}
	return max
}

func main() {
	scanner := makeScanner(1024)
	q := eGetInt(scanner)
	for i := 0; i < q; i++ {
		x := eGetLine(scanner)
		y := eGetLine(scanner)
		fmt.Println(countLCS(x, y))
	}
}

////////////////////////////////////////////////////////////////////////////////
// ライブラリ
////////////////////////////////////////////////////////////////////////////////
func makeScanner(maxByte int) *bufio.Scanner {
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Buffer(make([]uint8, 0, 8192), maxByte)
	return scanner
}
func makeWordScanner() *bufio.Scanner {
	scanner := makeScanner(8192)
	scanner.Split(bufio.ScanWords)
	return scanner
}
func eGetLine(r *bufio.Scanner) string {
	if r.Scan() {
		return r.Text()
	}
	err := r.Err()
	if err != nil {
		log.Fatal(err)
	}
	// EOF
	return ""
}
func eGetInt(r *bufio.Scanner) int {
	line := eGetLine(r)
	return eAtoi(line)
}
func eGetFields(r *bufio.Scanner) []string {
	line := eGetLine(r)
	return strings.Fields(line)
}
func eGetInts(r *bufio.Scanner) []int {
	fields := eGetFields(r)
	ints := make([]int, len(fields))
	for i := 0; i < len(ints); i++ {
		ints[i] = eAtoi(fields[i])
	}
	return ints
}
func eGetChars(r *bufio.Scanner) []string {
	line := eGetLine(r)
	return strings.Split(line, "")
}
func eAtoi(s string) int {
	n, err := strconv.Atoi(s)
	if err != nil {
		log.Fatal(err)
	}
	return n
}

type ints []int

func (s ints) String() string {
	var buf bytes.Buffer
	buf.WriteString("[")
	sep := ""
	for _, v := range s {
		buf.WriteString(fmt.Sprintf("%s%d", sep, v))
		sep = ", "
	}
	buf.WriteString("]")
	return buf.String()
}

func reverse(a ints) ints {
	r := make(ints, len(a))
	for i := 0; i < len(a); i++ {
		r[i] = a[len(a)-1-i]
	}
	return r
}
func max(a ints) (int, bool) {
	if len(a) == 0 {
		return 0, false
	}
	m := a[0]
	for _, e := range a {
		if e > m {
			m = e
		}
	}
	return m, true
}
func min(a []int) int {
	m := a[0]
	for _, v := range a {
		if v < m {
			m = v
		}
	}
	return m
}

func sum(a ints) int {
	if len(a) == 0 {
		return 0
	}
	sum := 0
	for _, e := range a {
		sum += e
	}
	return sum
}
func find(n int, a ints) int {
	for i, v := range a {
		if n == v {
			return i
		}
	}
	return -1
}

C++: #include<bits/stdc++.h>

using namespace std;


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

    vector<string> X(q), Y(q);
    int X_size, Y_size;

    vector<int> tmp(3, 0);

    for(int i = 0; i < q; i++) {
        cin >> X[i];
        cin >> Y[i];
    }

    for(int k = 0; k < q; k++) {
        X_size = X[k].size();
        Y_size = Y[k].size();

        // Xのi文字目までとTのj文字目までのLCSの長さdp[i][j]
        vector<vector<int> > dp(X_size+1, vector<int>(Y_size+1, 0));

        // 初期条件
        dp[1][0] = 0, dp[0][1] = 0;

        // dp開始
        for(int i = 1; i <= X_size; i++) {
            for(int j = 1; j <= Y_size; j++) {
                if(X[k][i-1] == Y[k][j-1]) {
                    tmp = {};
                    tmp.push_back(dp[i-1][j-1] + 1);
                    tmp.push_back(dp[i-1][j]);
                    tmp.push_back(dp[i][j-1]);
                    sort(tmp.begin(), tmp.end());
                    dp[i][j] = tmp.back();
                    // dp[i][j] = max({dp[i-1][j-1] + 1, dp[i-1][j], dp[i][j-1]});
                } else {
                    dp[i][j] = max(dp[i-1][j], dp[i][j-1]);
                }
            }
        }

        cout << dp[X_size][Y_size] << endl;
    }

	return 0;
}

C++: #include <bits/stdc++.h>

using namespace std;

using ll = long long;

// Longest Common Subsequence between X=x_1...x_m and Y=y_1...y_n
// O(mn)
// ALDS_1_10_C: verified
int main(){
    ll Q; cin >> Q;
    for(ll q=0;q<Q;q++){
        string X, Y; cin >> X >> Y;
        ll m = X.size(), n = Y.size();
        vector<vector<ll> > dp(m + 1, vector<ll>(n + 1));
        for(ll i=1;i<=m;i++){
            for(ll j=1;j<=n;j++){
                if(X[i-1] == Y[j-1]){
                    dp[i][j] = max(max(dp[i][j-1], dp[i-1][j]), dp[i-1][j-1] + 1);
                }else{
                    dp[i][j] = max(dp[i][j-1], dp[i-1][j]);
                }
            }
        }
        cout << dp[m][n] << endl;
    }
}

C++: #include <iostream>
#include <cstdio>
#include <algorithm>
#include <cmath>
#include <climits>
#include <string>
#include <vector>
#include <utility>
#include <functional>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <cassert>

using namespace std;

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

#define REP(i, n) for (ll i = 0; i < n; i++)
#define REPR(i, n) for (ll i = n; i >= 0; i--)
#define FOR(i, m, n) for (ll i = m; i < n; i++)

int dp[1001][1001];

int main() {
    int q;
    cin >> q;
    REP(i, q) {
        string s, t;
        cin >> s >> t;
        REP(i, s.size() + 1) REP(j, t.size() + 1) dp[i][j] = 0;
        REP(i, s.size()) {
            REP(j, t.size()) {
                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] = dp[i + 1][j];
                dp[i + 1][j + 1] = dp[i][j + 1];
            }
        }
        cout << dp[s.size()][t.size()] << endl;
    }
    return 0;
}

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

using namespace std;

int lcs(string x,string y){
  int m=x.size();
  int n=y.size();
  int c[m+1][n+1];
  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-1]==y[j-1]) 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 n; cin >> n;
  for(int i=0;i<n;i++){
    string x,y;
    cin >> x >> y;
    cout << lcs(x,y) << endl;
  }
}

C++: #include<stdio.h>

int strlen(char s[]) {
  int w = 0;
  while (1) {
    if (s[w] == '\0')
      break;
    w++;
  }
  return w;
}

int max(int a, int b, int c){
  int m = a;
  if (m < b)
    m = b;
  if (m < c)
    m = c;
  return m;
}

int main(void){
  int q, xl = 0, yl = 0, h = 0, i = 0, j = 0;
  int d, ans = 0;
  int DP[1001][1001];
  char X[1001], Y[1001];

  for (i = 0; i < 1001; i++) {
    DP[i][0] = 0;
  }
  for (i = 0; i < 1001; i++) {
    DP[0][i] = 0;
  }

  scanf("%d", &q);
  for (h = 0; h < q; h++) {

    scanf("%s", X);
    scanf("%s", Y);
    xl = strlen(X);
    yl = strlen(Y);

    for (i = 1; i <= xl; i++) {
       for (j = 1; j <= yl; j++) {
        if (X[i-1] == Y[j-1])
          d = 1;
        else
          d = 0;
        DP[i][j] = max(DP[i-1][j-1], DP[i-1][j], DP[i-1][j]) + d;
        if(DP[i][j] > ans)
          ans = DP[i][j];
      }
    }
    printf("%d\n", ans);
    ans = 0;
  }
  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;
  Y = ' ' + Y;
  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;
}