Go: package main

import (
	"bufio"
	"fmt"
	"os"
)

func main() {
	for q := ReadInt(); q > 0; q-- {
		x, y := ReadString(), ReadString()
		fmt.Println(LCS(x, y))
	}
}

func LCS(x, y string) int {
	dp := make([][]int, len(x)+1)
	for i := 0; i < len(x)+1; i++ {
		dp[i] = make([]int, len(y)+1)
	}
	for i := 0; i < len(x); i++ {
		for j := 0; j < len(y); j++ {
			dp[i+1][j+1] = Max(dp[i+1][j], dp[i][j+1])
			if x[i] == y[j] {
				dp[i+1][j+1] = Max(dp[i+1][j+1], dp[i][j]+1)
			}
		}
	}
	return dp[len(x)][len(y)]
}

func Max(xs ...int) int {
	max := xs[0]
	for _, x := range xs[1:] {
		if max < x {
			max = x
		}
	}
	return max
}

var reader = bufio.NewReader(os.Stdin)

func Scan(a ...interface{}) {
	if _, err := fmt.Fscan(reader, a...); err != nil {
		panic(err)
	}
}
func ReadInt() (i int)       { Scan(&i); return }
func ReadString() (s string) { Scan(&s); return }
func ReadInts(n int) []int {
	v := make([]int, n)
	for i := 0; i < n; i++ {
		Scan(&v[i])
	}
	return v
}

C++: #define _CRT_SECURE_NO_WARNINGS
#pragma warning(disable: 4244) // 最悪をします
#include <iostream>
#include <cmath>
#include <algorithm>
#include <vector>
#include <numeric>
#include <queue>
#include <stack>
#include <map> 
#include <set>
#include <string>
#include <functional>
#include <list>
#include <random>
#include <time.h>
#include <iomanip>
#include <assert.h>
#include <numeric>
#include <sstream>
#define BIT(nr) (1UL << (nr))
#define int long long
//#define ll long long
#define double long double
#define mod 1000000007
#define MAXN (int)1e+5 * 2+1
#define LL_MAX 9223372036854775807	//ない環境用
#define LL_HALFMAX 9223372036854775807 / 2	//ない環境用
#define MIN -(9223372036854775807 / 2)
#define REP(i,a,n) for(int i=(a); i<(int)(n); i++)
#define rep(i,n) REP(i,0,n)
#define FOR(it,c) for(__typeof((c).begin()) it=(c).begin(); it!=(c).end(); ++it)
#define ALLOF(c) (c).begin(), (c).end()
#define REPS(i,x) for(int i=1;i<=(int)(x);i++)
#define RREP(i,x) for(int i=((int)(x)-1);i>=0;i--)
#define RREPS(i,x) for(int i=((int)(x));i>0;i--)
#define repl(i,a,b) for(int i=(int)(a);i<(int)(b);i++)
#define mp make_pair
template<typename T1, typename T2> inline void chmin(T1 & a, T2 b) { if (a > b) a = b; }
template<typename T1, typename T2> inline void chmax(T1& a, T2 b) { if (a < b) a = b; }


using namespace std;

//デバッグ用カッコの有無
#ifdef DEBUG
template <class T>ostream &operator<<(ostream &o, const vector<T>&v)
{
	o << "{"; for (int i = 0; i<(int)v.size(); i++)o << (i>0 ? ", " : "") << v[i]; o << "}"; return o;
}
#endif // DEBUG

template <class T>ostream &operator<<(ostream &o, const vector<T>&v)
{
	for (int i = 0; i<(int)v.size(); i++)o << (i>0 ? " " : "") << v[i]; return o;
}

int dx[4] = { 0, 1, 0, -1 }; // x軸方向への変位
int dy[4] = { 1, 0, -1, 0 }; // y軸方向への変位

int dxp[4] = { 0, 1 }; // x軸方向への変位(正のみ)
int dyp[4] = { 1, 0 }; // y軸方向への変位(負のみ)

using Weight = int;
using Flow = int;
struct Edge {
	int src, dst;

	// libalgo のものに追加、メンバを追加するだけなので互換性は崩さないはず、逆辺のG[e.dstの]インデックスを保持
	int rev;
	Weight weight;
	Flow cap;
	Edge() : src(0), dst(0), weight(0) {}
	Edge(int s, int d, Weight w) : src(s), dst(d), weight(w) {}
};
using Edges = std::vector<Edge>;
using Graph = std::vector<Edges>;
using Array = std::vector<Weight>;
using Matrix = std::vector<Array>;

void add_edge(Graph& g, int a, int b, Weight w = 1) {
	g[a].emplace_back(a, b, w);
	g[b].emplace_back(b, a, w);
}
void add_arc(Graph& g, int a, int b, Weight w = 1) { g[a].emplace_back(a, b, w); }

void solve() {

}

int dp[30][50010];

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

	rep(_, q) {
		string s, t;
		cin >> s >> t;
		int sl = s.length();
		int tl = t.length();

		s = "*" + s;
		t = "*" + t;

		vector<vector<int>> dp(sl + 1, vector<int>(tl + 1, 0));

		REPS(i, sl) {
			REPS(j, tl) {
				if (s[i] == t[j]) {
					chmax(dp[i][j], dp[i - 1][j - 1] + 1);
				}
				chmax(dp[i][j], dp[i - 1][j]);
				chmax(dp[i][j], dp[i][j - 1]);

			}
		}

		cout << dp[sl][tl] << "\n";
	}

}

C++: #include<cstdlib>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<vector>
#include<queue>
#include<set>
using namespace std;
const int MAXN = (int)1e3 + 10;
const int INF = (int) 0x3f3f3f3f;
typedef long long LL;

int n;
int dp[MAXN][MAXN];
char a[MAXN],b[MAXN];

void work(){
    int q; scanf("%d",&q);
    while(q--){
        scanf("%s%s",a+1,b+1);
        int lena=strlen(a+1);
        int lenb=strlen(b+1);
        for(int i=1;i<=lena;i++)
            for(int j=1;j<=lenb;j++) dp[i][j]=INF;
        for(int i=1;i<=lena;i++){
            for(int j=1;j<=lenb;j++){
                dp[i][j]=max(dp[i-1][j],dp[i][j-1]);
                dp[i][j]=max(dp[i][j],dp[i-1][j-1]+(a[i]==b[j]));
            }
        }
        printf("%d\n",dp[lena][lenb]);
    }
}
/*
3
abcbdab
bdcaba
abc
abc
abc
bc
*/

int main(){
    work();
    return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define F first
#define S second
#define pii pair<int, int>
#define eb emplace_back
#define all(v) v.begin(), v.end()
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep3(i, l, n) for (int i = l; i < (n); ++i)
#define sz(v) (int)v.size()
#define inf (int)(1e9+7)
#define abs(x) (x >= 0 ? x : -(x))
template<typename T1, typename T2> inline void chmin(T1 &a, T2 b) { if (a > b) a = b; }
template<typename T1, typename T2> inline void chmax(T1 &a, T2 b) { if (a < b) a = b; }
template<typename T> inline T gcd(T a, T b) { if (b == 0) return a; return gcd(b, a % b); }







int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    
    
    
    
    int n;
    cin >> n;
    while (n--) {
        string s, t;
        cin >> s >> t;
        int dp[1003][1003] = {0};
        rep(i, sz(s) + 1) rep(j, sz(t) + 1) {
            chmax(dp[i + 1][j], dp[i][j]);
            chmax(dp[i][j + 1], dp[i][j]);
            chmax(dp[i + 1][j + 1], dp[i][j] + (s[i] == t[j]));
        }
        cout << dp[sz(s)][sz(t)] << endl;
        // rep(i, sz(s) + 1) { rep(j, sz(t) + 1) cout << dp[i][j] << " "; cout << endl; }
    }
}

C++: #include<math.h>
#include<limits.h>
#include<iostream>
#include<string>
#include<vector>
#include<stdio.h>
#include<sstream>
#include<list>
#include<queue>
#include<algorithm>
#include<functional>
#include<map>
#include<set>
#include<utility>
#include<initializer_list>
#include<tuple>
#include<regex>
using namespace std;
#define ull unsigned long long
#define ll long long
#define rep(i, n) for(int i=0;i<(int)(n);i++)
#define all(t) t.begin(), t.end()
bool isSubstring(string substr, string t) {
	int n = substr.length();
	int seek = 0;
	rep(i, n) {
		bool ex = 0;
		for (int j = seek; j < t.length(); j++) {
			if (substr[i] == t[j]) {
				ex = 1;
				seek = j + 1;
				break;
			}
		}
		if (ex) {
			continue;
		}
		else {
			return false;
		}
	}
	return true;

}

int LongestCommonSubstring(string s, string t) {
	vector<int>dp(s.length(), 0);
	int n = s.length();
	string lcs = "";
	if (isSubstring(s.substr(n - 1, n), t)) {

		dp[n - 1] = 1;
		lcs = s[n - 1];
	}
	for (int i = n - 2; i >= 0; i--) {
		//string substr = s.substr(i, n);
		string substr = s[i] + lcs;
		int issubst = isSubstring(substr, t);
		if (issubst) lcs = substr;
		dp[i] = dp[i + 1] + issubst;
	}
	return dp[0];
}
int main() {
	//cout << isSubstring("abc", "abcde") << endl;
	//cout << isSubstring("bd", "abcde") << endl;
	//cout << isSubstring("db", "abcde") << endl;

	//cout << LongestCommonSubstring("bacd", "becd") << endl;
	//cout << LongestCommonSubstring("abcd", "becd") << endl;
	int q;
	cin >> q;
	vector<string> s(q);
	vector<string> t(q);
	rep(i, q) {
		cin >> s[i] >> t[i];
	}
	rep(i, q) {
		cout << LongestCommonSubstring(s[i], t[i]) << endl;
	}

	return 0;
}