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++: #define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;
#define rep0(n) for (int counter = 0; counter < (int)(n); counter++)
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rep2(i, s, n) for (int i = s; i < (int)(n); i++)
#define rep3(i, s, n) for (int i = s; i > (int)(n); i--)
#define ALL(obj) obj.begin(), obj.end()
#define from1(obj) obj.begin() + 1, obj.end()
#define db(x) cerr << #x << ":" << (x) << " "
#define dbl(x) cerr << #x << ":" << (x) << "\n"
#define db2(x, y) cerr << #x << ":" << (x) << ", " << #y << ":" << (y) << " "
#define db2l(x, y) cerr << #x << ":" << (x) << ", " << #y << ":" << (y) << "\n"
#define dbl2(x, y) cerr << #x << ":" << (x) << "\n" << #y << ":" << (y) << "\n"
#define db3(x, y, z) cerr << #x << ":" << (x) << ", " << #y << ":" << (y) << " " << #z << ":" << (z) << " "
#define db3l(x, y, z) cerr << #x << ":" << (x) << ", " << #y << ":" << (y) << ", " << #z << ":" << (z) << "\n"
#define dbl3(x, y, z) cerr << #x << ":" << (x) << "\n" << #y << ":" << (y) << "\n" << #z << ":" << (z) << "\n"
#define dbp(p) cerr << #p << ":(" << p.first << ", " << p.second << ") "
#define dbpl(p) cerr << #p << ":(" << p.first << ", " << p.second << ")\n"
#define dbt3(t3) cerr << #t3 << ":(" << get<0>(t3) << ", " << get<1>(t3) << ", " << get<2>(t3) << ") "
#define dbt3l(t3) cerr << #t3 << ":(" << get<0>(t3) << ", " << get<1>(t3) << ", " << get<2>(t3) << ")\n"
#define dbt4(t4) cerr << #t4 << ":(" << get<0>(t4) << ", " << get<1>(t4) << ", " << get<2>(t4) << ", " << get<3>(t4) << ") "
#define dbt4l(t4) cerr << #t4 << ":(" << get<0>(t4) << ", " << get<1>(t4) << ", " << get<2>(t4) << ", " << get<3>(t4) << ")\n"
#define dbv(vec) cerr << #vec << ":{ "; for (auto e : vec) cerr << e << ", "; cerr << "}\n"
#define dbvp(vec) cerr << #vec << ":{ "; for (auto p : vec) cerr << "(" << p.first << ", " << p.second << "), "; cerr << "}\n"
#define dbvv(vv) cerr << #vv << ":{\n"; for (auto vec : vv) { cerr << "{ "; for (auto e : vec) cerr << e << ", "; cerr << "}\n"; } cerr << "}\n"
#define dbm(map) cerr << #map << ":{ "; for (auto p : map) cerr << "(" << p.first << ", " << p.second << "), "; cerr << "}\n"
#define YN(f) cout << (f ? "YES" : "NO") << "\n"
#define Yn(f) cout << (f ? "Yes" : "No") << "\n"
#define yn(f) cout << (f ? "yes" : "no") << "\n"
using ll = long long;
using vi = vector<int>; using vl = vector<ll>; using vs = vector<string>; using vb = vector<bool>;
using vvi = vector<vi>; using vvl = vector<vl>; using vvb = vector<vb>;
using pii = pair<int, int>; using pil = pair<int, ll> ; using pli = pair<ll, int>; using pll = pair<ll, ll>;
using vpii = vector<pii>; using vpll = vector<pll>;
using ti3 = tuple<int, int, int>; using tl3 = tuple<ll, ll, ll>;
using ti4 = tuple<int, int, int, int>; using tl4 = tuple<ll, ll, ll, ll>;
using mii = map<int, int>; using mil = map<int, ll>; using mli = map<ll, int>; using mll = map<ll, ll>;

void LCS() {
	string s, t; cin >> s >> t;
	vvi dp(s.size() + 1, vi(t.size() + 1)); // dp[i][j]: s[0]~s[i-1]とt[0]~t[j-1]のLCSの長さ
	rep(i, s.size()) {
		rep(j, t.size()) {
			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[s.size()][t.size()] << endl;
}

int main() {
	int q; cin >> q;
	rep0(q) LCS();	
}

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

void solve(){
    int Q;
    cin >> Q;
    while(Q--){
        string S, T;
        cin >> S >> T;
        int s_len = S.size();
        int t_len = T.size();
        
        vector<vector<int>> dp(s_len+1, vector<int>(t_len+1, 0));
        
        int ans = 0;
        for(int i=0; i<s_len; i++){
            for(int j=0; j<t_len; 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]);

                ans = max(ans, dp[i+1][j+1]);
            }
        }
        cout << ans << endl;
        
    }
}


signed main(){
    cout << fixed << setprecision(18);
    cerr << fixed << setprecision(18);
    solve();
}