Go: package main

import (
	"bufio"
	"os"
	"io"
	"strconv"
	"math"
	"fmt"
)

var (
	nstr   func() string
	stdout *bufio.Writer
)

func init() {
	nstr = newReadString(os.Stdin)
	stdout = bufio.NewWriter(os.Stdout)
}

func main() {
	defer stdout.Flush()

	n := nint()
	xList := make([]string, n)
	yList := make([]string, n)

	for i:=0;i<n ;i++  {
		xList[i] = nstr()
		yList[i] = nstr()
	}

	for i := 0; i<n	; i++  {
		fmt.Println(lcs(xList[i], yList[i]))
	}

}

func lcs(x string, y string) int{
	var m = len(x)
	var n = len(y)

	c := make([][]int, m+1)
	for i:= range c{
		c[i] = make([]int, n+1)
	}
	for i:=	1;i<=m ;i++  {
		for 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] = int(math.Max(float64(c[i-1][j]), float64(c[i][j-1])))
			}


		}
	}
	return c[m][n]

}


func newReadString(ior io.Reader) func() string {
	r := bufio.NewScanner(ior)
	r.Buffer(make([]byte, 1024), int(1e+11))
	r.Split(bufio.ScanWords)

	return func() string {
		if !r.Scan() {
			panic("Scan failed")
		}
		return r.Text()
	}
}

func nint64() int64 {
	i, err := strconv.ParseInt(nstr(), 0, 64)
	if err != nil {
		panic(err.Error())
	}
	return i
}

func nint() int {
	return int(nint64())
}

func getIntSlice(n int) []int {
	b := make([]int, n)
	for i := 0; i < n; i++ {
		b[i] = nint()
	}
	return b
}

func getStringSlice(n int) []string {
	b := make([]string, n)
	for i := 0; i < n; i++ {
		b[i] = nstr()
	}
	return b
}

func gcd(x, y int) int {
	if y == 0 {
		return x
	}
	return gcd(y, x%y)
}

func lcm(x, y int) int {
	return x * y / gcd(x, y)
}

func contains(s []int, e int) bool {
	for _, a := range s {
		if a == e {
			return true
		}
	}
	return false
}

func bin(i int, prefix bool) string {
	i64 := int64(i)

	if prefix {
		return "0b" + strconv.FormatInt(i64, 2)
	} else {
		return strconv.FormatInt(i64, 2)
	}
}

func strReverse(s string) string {
	runes := []rune(s)
	for i, j := 0, len(runes)-1; i < j; i, j = i+1, j-1 {
		runes[i], runes[j] = runes[j], runes[i]
	}

	return string(runes)
}

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

using namespace std;

int main() {
	int q;
	string strX, strY;

	cin >> q;
	for (int n = 0; n < q; n++) {
		cin >> strX;
        cin >> strY;
		char X[strX.length() + 1];
		for (int x = 0; x < strX.length(); x++) {//文字列を配列に入れる
			X[x + 1] = strX[x];
		}

        char Y[strY.length() + 1];
		for (int y = 0; y < strY.length(); y++) {//文字列を配列に入れる
			Y[y + 1] = strY[y];
		}

        int c[strX.length()+1][strY.length()];
        int maxLen = 0;

		for (int i = 0; i<=strX.length(); i++){
            for(int j = 0; j<=strY.length(); j++){
                if(i == 0 || j == 0){
                    c[i][j] = 0;
                }
                else 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]);
                }

                if(c[i][j] > maxLen){
                    maxLen = c[i][j];
                }
            }
        }
        cout << maxLen << endl;
	}

    return 0;
}

C++: #include <bits/stdc++.h>
#define debug(x) cerr << #x << ": " << x << '\n';
using namespace std;
using ll = long long;
using P = pair<int, int>;
const int INF = (int)1e9;
const int MOD = (int)1e9 + 7;

int dp[1001][1001];

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

	vector<int> res;
	for(int i = 0; i < q; i++){
		string s, t;
		cin >> s >> t;

		fill(dp[0], dp[1000] + 1000, 0);
		for(int j = 0; j < s.size(); j++){
			for(int k = 0; k < t.size(); k++){
				if(s[j] == t[k]) dp[j+1][k+1] = dp[j][k] + 1;
				else dp[j+1][k+1] = max(dp[j+1][k], dp[j][k+1]);
			}
		}

		res.push_back(dp[s.size()][t.size()]);
	}

	for(int i = 0; i < q; i++) cout << res[i] << '\n';

	return 0;
}

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

int dp[1001][1001];
string str1, str2;
int n;

int solve(string str1, string str2) {
  memset(dp, 0, sizeof(dp));
  for(int r = 0; r < str2.size(); r++) {
    for(int c = 0; c < str1.size(); c++) {
      if(str2[r] == str1[c]) {
        dp[r + 1][c + 1] = dp[r][c] + 1;
      }
      else {
        dp[r + 1][c + 1] = max(dp[r + 1][c], dp[r][c + 1]);
      }
    }
  }
  return dp[str2.size()][str1.size()];
}

int main() {
  cin >> n;
  for(int i = 0; i < n; i++) {
    cin >> str1 >> str2;
    cout << solve(str1, str2) << endl;
  }
}

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

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(0);
    int n;
    std::cin >> n;
    std::string s1, s2;
    for (int q=0; q<n; q++) {
        std::cin >> s1 >> s2;
        int m1 = s1.size()+1;
        int m2 = s2.size()+1;
        int* dp = (int*)malloc(m1*m2*sizeof(int));
        for (int i=0; i<m1; i++) {
            dp[i*m2]=0;
        }
        for (int i=0; i<m2; i++) {
            dp[i]=0;
        }
        for (int i=1; i<m1; i++) {
            int leftmax=0;
            for (int j=1; j<m2; j++) {
                dp[i*m2+j] = leftmax;
                if (s1[i-1] == s2[j-1]) {
                    dp[i*m2+j]+=1;
                }
                if (dp[(i-1)*m2+j] > leftmax) {
                    leftmax = dp[(i-1)*m2+j];
                }
                if (dp[i*m2+j] < dp[(i-1)*m2+j]) {
                    dp[i*m2+j] = dp[(i-1)*m2+j];
                }
            }
        }
        int max=0;
        for (int i=0; i<m2; i++) {
            if (dp[(m1-1)*m2+i] > max) {
                max = dp[(m1-1)*m2+i];
            }
        }
        std::cout << max << "\n";
        free(dp);
    }

    return 0;
}

C++: #include<iostream>
#include<cstring>
#include<string>
#include<algorithm>
using namespace std;
const int maxn = 1005;

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();
		cout << lcs() << endl;
	}
	return 0;
}

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

using std::cin;
using std::cout;
using std::cerr;
using std::endl;

// 最長共通部分列 ... len(s) == m, len(t) == n とすると, O(mn)
int lcs(std::string s, std::string t) {
  std::vector<std::vector<int> > dp(s.size() + 1, std::vector<int>(t.size() + 1, 0));

  for (int i = 0; i < s.size(); ++i) {
    for (int j = 0; j < t.size(); ++j) {
      if (s[i] == t[j]) {
        dp[i][j] = (i == 0 ? (j == 0 ? 1 : 0) : ;
      }
      else if (i >= 0 && j >= 0 && dp[i - 1][j] >= dp[j][i - 1]) {
        dp[i][j] = dp[i - 1][j];
      }
      else if (i >= 0 && j >= 0) {
        dp[i][j] = dp[i][j - 1];
      }
    }
  }

  return dp[s.size()][t.size()];
}

int main() {
  int q;
  std::string s, t;
  cin >> q;
  for (int i = 0; i < q; ++i) {
    cin >> s >> t;
    cout << lcs(s, t) << endl;
  }

  return 0;
}