Go: package main

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

//Util
func nextStr() string {
	sc.Scan()
	return sc.Text()
}

func nextInt() int {
	sc.Scan()
	i, e := strconv.Atoi(sc.Text())
	if e != nil {
		panic(e)
	}
	return i
}

func maxInt(a, b int) int {
	if a > b {
		return a
	} else {
		return b
	}
}

func minInt(a, b int) int {
	if a > b {
		return b
	} else {
		return a
	}
}

func absInt(a int) int {
	if a >= 0 {
		return a
	} else {
		return -a
	}
}

func absFloat64(a float64) float64 {
	if a >= 0 {
		return a
	} else {
		return -a
	}
}

func minFloat64(a, b float64) float64 {
	if a > b {
		return b
	} else {
		return a
	}
}

func str2Int(s string) int {
	n, _ := strconv.Atoi(s)
	return n
}

//Main
var sc = bufio.NewScanner(os.Stdin)
var q int
var X, Y string

func lcs(X, Y string) int {
	lenX := len(X)
	lenY := len(Y)
	dp := make([][]int, lenX+1)
	for i := 0; i < lenX+1; i++ {
		dp[i] = make([]int, lenY+1)
	}

	res := 0
	for i := 1; i < lenX+1; i++ {
		for j := 1; j < lenY+1; j++ {
			if X[i-1] == Y[j-1] {
				dp[i][j] = dp[i-1][j-1] + 1
			} else {
				dp[i][j] = maxInt(dp[i-1][j], dp[i][j-1])
			}
			//fmt.Println(dp)
			res = maxInt(res, dp[i][j])
		}

	}
	return res
}

func main() {
	sc.Split(bufio.ScanWords)
	q = nextInt()

	for i := 0; i < q; i++ {
		X = nextStr()
		Y = nextStr()

		fmt.Println(lcs(X, Y))
	}
}

C++: // aribon2-3-2_a
#include <bits/stdc++.h>
#ifdef LOCAL
#include "../cxx-prettyprint/prettyprint.hpp"
#endif
using namespace std;

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

#define REP(i, n) for (int (i) = 0 ; (i) < (int)(n) ; ++(i))
#define REPN(i, m, n) for (int (i) = m ; (i) < (int)(n) ; ++(i))
#define REP_REV(i, n) for (int (i) = (int)(n) - 1 ; (i) >= 0 ; --(i))
#define REPN_REV(i, m, n) for (int (i) = (int)(n) - 1 ; (i) >= m ; --(i))
#define ALL(x) x.begin(), x.end()

#define INF ((1 << 29)-1)
#define MOD (1000000007)

#define print2D(h, w, arr) REP(i, h) { REP(j, w) cout << arr[i][j] << " "; cout << endl; }
template<class T> void print(const T& x){cout << x << endl;}
template<class T, class... A> void print(const T& first, const A&... rest) { cout << first << " "; print(rest...); }
struct PreMain {PreMain(){cin.tie(0);ios::sync_with_stdio(false);cout<<fixed<<setprecision(20);}} premain;

int main() {
#ifdef LOCAL
    ifstream in("../arg.txt");
    cin.rdbuf(in.rdbuf());
#endif

    int N;
    cin >> N;
    string A,B;
    REP(n, N){
        cin >> A >> B;
        int dp[A.size()+1][B.size()+1] = {};

        REP(i, A.size()){
            REP(j, B.size()){
                if (A[i] == B[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]);
                }

            }
        }
        print(dp[A.size()][B.size()]);
    }

    return 0;
}

C++: #include <iostream>
#include <sstream>
#include <cstdio>
#include <cmath>
#include <cctype>
#include <string>
#include <vector>
#include <list>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <algorithm>
#include <functional>

using namespace std;
using ll = long long int;
#define rep(i,n) for(int i = 0; i < n; i++)
#define FOR(i, a, b)  for(int i = (a); i < (b) ; i++)
#define pb push_back
#define SORT(v,n) sort(v, v+n)
#define ALL(x) (x).begin(),(x).end()
#define debug(x) cerr << #x << ": " << x << '\n'
#define elif else if
#define itn ll
#define int ll
const int INF = 100100100;
const int MOD = (int)1e9 + 7;
const double EPS = 1e-9;
///                →,↑,←,↓,↗,↖,↙,↘
int dx[8] = { 1, 0, -1, 0, 1, -1, -1, 1 };
int dy[8] = { 0, 1, 0, -1, 1, 1, -1, -1 };


static const int N = 1000;

int lcs(string X, string Y) {
	int c[N + 1][N + 1];
	int maxl = 0;
	int i, j;
	int m = X.size();
	int n = Y.size();
	X = ' ' + X;
	Y = ' ' + Y;
	FOR(i, 1, m+1) {
		c[i][0] = 0;
	}
	FOR(i, 1, n+1) {
		c[0][i] = 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(c[i][j], maxl);
		}
	}
	return maxl;
}

signed main() {
	ios::sync_with_stdio(false);
	int n;
	string s1, s2;
	cin >> n;
	int i;
	rep(i, n) {
		cin >> s1 >> s2;
		cout << lcs(s1, s2) << "\n";
	}
	return 0;
}

C++: #include <iostream>
#include <vector>
#include <numeric>

using namespace std;

int main() {
    int32_t q;
    cin >> q;

    while (q--) {
        string X, Y;
        cin >> X >> Y;

        vector<int32_t> lcs((X.size()+1)*(Y.size()+1));
        fill(lcs.begin(), lcs.end(), 0);

        for (int32_t i = 1; i <= X.size(); i++) {
            for (int32_t j = 1; j <= Y.size(); j++) {
                lcs[i*(Y.size()+1)+j] = max(lcs[(i-1)*(Y.size()+1)+j], lcs[i*(Y.size()+1)+j-1]);
                if (X[i-1] == Y[j-1]) {
                    lcs[i*(Y.size()+1)+j] = max(lcs[i*(Y.size()+1)+j], lcs[(i-1)*(Y.size()+1)+j-1] + 1);
                }
            }
        }

        cout << lcs.back() << endl;

    }

    return 0;
}

C++: #include <bits/stdc++.h>
#define int long long
#define double long double
#define rep(i, a, n) for(int i = (int)(a);(i) < (int)(n);++(i))
#define repe(i, a, n) for(int i = (int)(a);(i) <= (int)(n);++(i))
#define repif(i, a, x) for(int i = (int)(a);(x);++(i))
#define repr(i, a, n) for(int i = ((int)(a)-1);(i) >= (int)(n);--(i))
#define reper(i, a, n) for(int i = (int)(a);(i) >= (int)(n);--(i))
#define SZ(x) ((int)(x).size())
#define ALL(x) begin(x), end(x)
#define CEIL(x) ((int)ceil(((double)x)))
#define POW(x, y) ((int)pow(x, y))
#define UNIQUE(x) (x).erase(unique(ALL((x))), end(x))
#define gcd(x, y) __gcd(x, y)
#define lcm(x, y) ((x)/gcd(x,y)*(y))
#define isin(x, l, r) ((l) <= (x) and (x) < (r))
#define fcout(n) cout << fixed << setprecision(n)
#define rcout(n) cout << right << setw(n)
#define pb push_back
#define eb emplace_back
#define lb lower_bound
#define ub upper_bound
#define PI (acosl(-1))
#define EPS (1e-10)
#define INF LLONG_MAX
#define INF32 INT32_MAX
#define MOD 1000000007LL
using namespace std;
using VI = vector<int>;
using PII = pair<int, int>;
using TIII = tuple<int, int, int>;
using VPII = vector<PII>;
using VTIII = vector<TIII>;
using Complex = complex<double>;
template<typename T, template<typename> typename C = less> using PQ = priority_queue<T, vector<T>, C<T>>;
template<typename T> inline bool chmax(T& a, const T& b, bool t = false){ if(a<b or (t and a == b)){ a=b; return true; } return false; }
template<typename T> inline bool chmin(T& a, const T& b, bool t = false){ if(a>b or (t and a == b)){ a=b; return true; } return false; }


signed main(){
    int q;
    cin >> q;
    while(q--){
        string X, Y;
        cin >> X >> Y;
        vector<VI> dp(SZ(X)+1, VI(SZ(Y)+1));
        rep(i, 0, SZ(X)) rep(j, 0, SZ(Y)){
            if(X[i] == Y[j]) dp[i+1][j+1] = dp[i][j]+1;
            else chmax(dp[i+1][j+1], max(dp[i+1][j], dp[i][j+1]));
        }
        cout << dp[SZ(X)][SZ(Y)] << endl;
    }

    return 0;
}

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

#define NUM 1000
int dp[NUM + 1][NUM + 1];

void calc(string X, string Y){
    for(int i = 0; i <= X.size(); i++){
        for(int j = 0; j <= Y.size(); j++){
            dp[i][j] = 0;
        }
    }

    for(int j = 1; j <= Y.size(); j++){
        for(int i = 1; i <= X.size(); i++){
            if(X[i - 1] == Y[j - 1]){
                dp[i][j] = dp[i - 1][j - 1] + 1;
            }else{
                dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]);
            }
        }
    }
    
    printf("%d\n", dp[X.size()][Y.size()]);

}

int main(void){
    int q;
    scanf("%d", &q);

    for(int i = 0; i < q; i++){
        string X;
        string Y;
        cin >> X;
        cin >> Y;
        calc(X, Y);
    }
}