Go: package main

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

func getScanner(fp *os.File) *bufio.Scanner {
	scanner := bufio.NewScanner(fp)
	scanner.Split(bufio.ScanWords)
	scanner.Buffer(make([]byte, 500001), 500000)
	return scanner
}

func getNextString(scanner *bufio.Scanner) string {
	scanner.Scan()
	return scanner.Text()
}

func getNextInt(scanner *bufio.Scanner) int {
	i, _ := strconv.Atoi(getNextString(scanner))
	return i
}

func main() {
	fp := os.Stdin
	if len(os.Args) > 1 {
		fp, _ = os.Open(os.Args[1])
	}

	scanner := getScanner(fp)
	writer := bufio.NewWriter(os.Stdout)

	n := getNextInt(scanner)
	for i := 0; i < n; i++ {
		x := getNextString(scanner)
		y := getNextString(scanner)

		fmt.Fprintln(writer, lcs(x, y))
	}

	writer.Flush()
}

func lcs(x, y string) int {
	lx := len(x)
	ly := len(y)
	dp := make([][]int, lx+1)
	for i := 0; i <= lx; i++ {
		dp[i] = make([]int, ly+1)
	}
	for i := 0; i < lx; i++ {
		for ii := 0; ii < ly; ii++ {
			if x[i] == y[ii] {
				dp[i+1][ii+1] = dp[i][ii] + 1
				continue
			}
			dp[i+1][ii+1] = dp[i][ii+1]
			if dp[i+1][ii] > dp[i+1][ii+1] {
				dp[i+1][ii+1] = dp[i+1][ii]
			}
		}
	}
	return dp[lx][ly]
}

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

using namespace std;
static const int N = 150;
static const int AX = 1000, AY = 1000;
string  X, Y;

int do_dp(int ax,int ay) {

    int dp[AX][AY];

    for (int i = 0; i < AX; i++) {
        for (int j = 0; j < AY; j++) {
            dp[i][j] = 0;
        }
    }

    for (int i = 0; i < ax; i++) {
        if (X[i] == Y[0]) dp[i][0] = 1;
        if (i > 0) dp[i][0] = max(dp[i][0], dp[i - 1][0]);
    }

    for (int j = 0; j < ay; j++) {
        if (X[0] == Y[j]) dp[0][j] = 1;
        if (j > 0) dp[0][j] = max(dp[0][j], dp[0][j - 1]);
    }

    for (int i = 1; i < ax; i++) {
        for (int j = 1; j < ay; j++) {
            if (X[i] == Y[j]) {
                dp[i][j] = dp[i - 1][j - 1] + 1;
            }
            else {
                dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]);
            }
        }
    }

    for(int i = 0;i < ax;i++){
    for(int j = 0;j < ay;j++){
    cout << dp[i][j] << " ";
    }
    cout << '\n';
    }

    return dp[ax - 1][ay - 1];
}

int main() {
    int q;

    cin >> q;

    int A[N];

    for (int i = 0; i < q; i++) {
        cin >> X;
        cin >> Y;
        //cout << X.size() << " " << Y.size() << '\n';
        A[i] = do_dp(X.size(),Y.size());
    }

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

    return 0;
}

C++: #include<iostream>
#include<algorithm>
#include<string>
#define MAX 10
using namespace std;

string x, y;

int lcs(int m, int n);

int main() {
	int i, q, n, m;
	cin >> q;
	for (i = 0; i < q; i++) {
		cin >> x >> y;
		cout << lcs(x.length(), y.length()) << endl;
	}
	return 0;
}

int lcs(int m, int n) {
	int i, j, maxl = 0, c[MAX][MAX];
	c[0][0] = 0;
	for (i = 1; i <= m; i++)c[i][0] = 0;
	for (j = 1; j <= n; j++)c[0][j] = 0;
	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] = max(c[i][j - 1], c[i - 1][j]);
			maxl = max(maxl, c[i][j]);
		}
	}
	return maxl;
}

C++: #include <bits/stdc++.h>
#define rep(i, n) for (int i=0; i<(n); ++i)
#define repr(i, a, b) for (int i=a; i<(b); ++i)
#define reprev(i, n) for (int i=n-1; i>=0; --i)
#define reprrev(i, a, b) for (int i=b-1; i>=(a); --i)
using namespace std;
using ll = long long;
using P = pair<int, int>;

int main() {
    cout << fixed << setprecision(10);
    
    int q; cin >> q;
    rep(i, q) {
        string s, t; cin >> s >> t;
        vector<vector<int>> dp(s.size()+1, vector<int>(t.size()+1));

        rep(j, s.size()) {
            rep(k, t.size()) {
                if (s[j] == t[k]) {
                    dp[j+1][k+1] = max(dp[j][k] + 1, dp[j+1][k]);
                    dp[j+1][k+1] = max(dp[j+1][k+1], dp[j][k+1]);
                } else {
                    dp[j+1][k+1] = max(dp[j][k+1], dp[j+1][k]);
                }
            }
        }
        cout << dp[s.size()][t.size()] << endl;
    }
    return 0;
}

C++: #include <set>
#include <map>
#include <list>
#include <queue>
#include <stack>
#include <cmath>
#include <ctype.h>
#include <ctime>
#include <cstdio>
#include <vector>
#include <string>
#include <bitset>
#include <cctype>
#include <cstdlib>
#include <cstring>
#include <utility>
#include <numeric>
#include <complex>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <cassert>
#include <iostream>
#include <iterator>
#include <algorithm>

using namespace std;

int lcs(string X,string Y){
	int m = X.size();
	int n = Y.size();
	int maxi = 0; 
	int C[m+1][n+1];
	X = ' ' + X;
	Y = ' ' + Y;
	for(int i = 1;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] == Y[j]){
				C[i][j] = C[i-1][j-1] + 1;
			}else{
				C[i][j] = max(C[i-1][j],C[i][j-1]);
			}
			maxi = max(maxi,C[i][j]);
		}
	}
	return maxi;
}

int main(){
	int n;
	cin >> n;
	string x,y;
	for(int i = 0 ;i < n;i++){
		cin >> x >> y;
		cout << lcs(x,y) << endl;;
	}
	return 0;
}

C++: #include <vector>
#include <algorithm>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstring>
//#include <chrono> //1e+9で割る auto end= chrono::system_clock::now()-st;  cout<<end.count()%1e+9<<endl;
using namespace std;
typedef long long ll;
typedef pair<int,int> P;
typedef pair<ll,ll> LP;
typedef long double db;

#define fr first
#define sc second
#define pb push_back
#define rep(i,x) for(int i=0;i<x;i++)
#define rep1(i,x) for(int i=1;i<=x;i++)
#define rrep(i,x) for(int i=x-1;i>=0;i--)
#define rrep1(i,x) for(int i=x;i>0;i--)

int q;
string s1,s2;
int ans;
int dp[1510][1501];
int main()
{
	cin>>q;
	rep(i,q){
		cin>>s1>>s2;
		rep(i,s1.size()){
			rep(j,s2.size()){
				dp[i][j]=0;
			}
		}
		if(s1[0]==s2[0]) dp[0][0]=1;
		rep1(i,s1.size()-1){
			if(s1[i]==s2[0]) dp[i][0]=1;
			dp[i][0]=max(dp[i][0],dp[i-1][0]);
		}
		rep1(i,s2.size()-1){
			if(s1[0]==s2[i]) dp[0][i]=1;
			dp[0][i]=max(dp[0][i],dp[0][i-1]);
		}
		rep1(i,s1.size()-1){
			rep1(j,s2.size()-1){
				dp[i][j]=max( dp[i-1][j], dp[i][j-1] );
				if(s1[i]==s2[j]) dp[i][j]= max(dp[i][j],dp[i-1][j-1]+1);
			}
		}
		cout<<dp[s1.size()-1][s2.size()-1]<<endl;
	}
}

C++: #include<iostream>
#include<cstdio>
#include<algorithm>
#include<vector>

using namespace std;

typedef pair<int,int> pii;

vector<pii> P;

string s,t,rev;

const int MAX_N = 1001;

int dp[MAX_N][MAX_N];

void trace(int i,int j){
	if(dp[i][j] == dp[i-1][j] && dp[i][j] == dp[i][j-1]){
		trace(i-1,j-1);	//??????????§????
	}else if(dp[i][j] == dp[i-1][j]){
		trace(i-1,j);	//???????§????
	}else if(dp[i][j] == dp[i][j-1]){
		trace(i,j-1);	//???????§????
	}else{
		rev += s[i-1];
		if(dp[i-1][j-1] == 0){
			return;
		}
		trace(i-1,j-1);	//??????????§????
	}
}
int main()
{
	string com;
	int n;
	cin >> n;
	for(int l=0;l<n;l++){
	cin >> s;
	cin >> t;
	for(int i=0;i<=s.length();i++){
		dp[i][0] = 0;
	}
	for(int i=0;i<=t.length();i++){
		dp[0][i] = 0;
	}
	for(int i=1;i<=s.length();i++){
		for(int j=1;j<=t.length();j++){
			if(s[i] == t[j]){
				dp[i][j] = dp[i-1][j-1]+1;
			}else{
				dp[i][j] = max(dp[i][j-1],dp[i-1][j]);
			}
		}
	}
	printf("%d\n",dp[s.length()][t.length()]);
	fill(dp[0],dp[s.length()+1],0);
	}
	/*
	trace(s.length(),t.length());
	for(int i=rev.length();i>0;i--){
		com += rev[i-1];
	}
	cout << com << "\n";	//????????±?????¨???????????????????????????
	*/
}