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 <bits/stdc++.h>
using namespace std;

int main()
{
    int n;
    cin >> n;

    string x, y;
    while (n--)
    {
        cin >> x >> y;
        int c[x.size() + 1][y.size() + 1];
        for (int i = 0; i <= x.size(); i++)
            c[i][0] = 0;
        for (int i = 0; i <= y.size(); i++)
            c[0][i] = 0;

        for (int i = 1; i <= x.size(); i++)
        {
            for (int j = 1; j <= y.size(); j++)
            {
                if (x[i - 1] == y[j - 1])
                    c[i][j] = c[i - 1][j - 1] + 1;
                else
                    c[i][j] = max(c[i - 1][j], c[i][j - 1]);
            }
        }
        cout << c[x.size()][y.size()] << endl;
    }
}

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

using namespace std;

int solve(string x, string y, int xlen, int ylen) {
    vector<vector<int>> dp(xlen + 1, vector<int>(ylen + 1, 0));
    for (int i = 1; i < xlen + 1; i++) {
        for (int j = 1; j < ylen + 1; j++) {
            if (x[i - 1] == y[j - 1]) {
                dp[i][j] = dp[i - 1][j - 1] + 1;
            }
            else {
                dp[i][j] = max(dp[i][j - 1], dp[i - 1][j]);
            }
        }
    }
    return dp[xlen][ylen];
}

int main() {

    int n;
    string x, y;

    cin >> n;
    
    for (int i = 0; i < n; i++) {
        cin >> x >> y;

        cout << solve(x, y, x.length(), y.length()) << endl;

    }
    
    return 0;
}

C++: #include <iostream>
#include <string>
#include <algorithm>
#include <functional>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <bitset>
#include <map>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
using namespace std;
typedef long long ll;
typedef pair<int,int> pint;
typedef vector<int> vint;
typedef vector<pint> vpint;
#define mp make_pair
#define fi first
#define se second
#define all(v) (v).begin(),(v).end()
#define rep(i,n) for(int i=0;i<(n);i++)
#define reps(i,f,n) for(int i=(f);i<(n);i++)
int dx[4] = {1, 0, 0, -1};
int dy[4] = {0, 1, -1, 0};

void slove(string X, string Y){
	int dp[1000][1000];//dp[X?????????][Y?????????] = LCS
	int sizex = X.size();
	int sizey = Y.size();

	//???????????????????????????????????????????????????0????????????????????\?????????
	X = ' ' + X;
	Y = ' ' + Y;

	reps(i, 1, sizex + 1) dp[i][0] = 0;//?????????????????????0??????dp???0
	reps(i, 1, sizey + 1) dp[0][i] = 0;//?????????????????????0??????dp???0

	int ans = 0;//????°??????????
	reps(i, 1, sizex + 1){
		reps(j, 1, sizey + 1){
			if(X[i] == Y[j]) dp[i][j] = dp[i - 1][j - 1] + 1;
			else if(X[i] != Y[j]) dp[i][j] = max(dp[i][j - 1], dp[i - 1][j]);

			ans = max(ans, dp[i][j]);
		}
	}
	printf("%d\n", ans);
	return;
}

int main(void){
	int n; cin >> n;
	string s1, s2;
	rep(i, n){
		cin >> s1 >> s2;
		slove(s1, s2);
	}
	return 0;
}

C++: #include<stdio.h>
#include<string>
#include<iostream>
#include<algorithm>
using namespace std;
string a;
string b;
int ans[1000+1][1000+1];
int lcs()
{
    int al=a.size();
    int bl=b.size();
    int maxn=-1;
    a=" "+a;
    b=" "+b;
    for (int i=1;i<=al;i++)
    {
        for (int j=1;j<=bl;j++)
        {
            if(a[i]==b[j])
            {
                ans[i][j]=ans[i-1][j-1]+1;
            }
            else {
                ans[i][j]=max(ans[i-1][j],ans[i][j-1]);
            }
            if(ans[i][j]>maxn)
                maxn=ans[i][j];
        }
    }
   return maxn;
}
int main()
{
    int q;
    scanf("%d",&q);
    for(int i=1;i<=q;i++)
    {
        cin>>a;
        cin>>b;
        int sum=lcs();
        cout<<sum<<endl;
    }
    return 0;
}

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

int main(){
  int q;
  cin >> q;
  string X,Y;

  for(int i=0;i<q;i++){
    cin >> X >> Y;
    int dp[1001][1001]={};
    for(int j=1;j<=Y.size();j++){
      for(int k=1;k<=X.size();k++){
	if(X[k-1]==Y[j-1]) dp[j][k]=dp[j-1][k-1]+1;
	else dp[j][k]=max(dp[j-1][k],dp[j][k-1]);
      }
    }
    cout << dp[Y.size()][X.size()] << endl;
  }
}

C++: #include<bits/stdc++.h>
#define range(i,a,b) for(int i = (a); i < (b); i++)
#define rep(i,b) for(int i = 0; i < (b); i++)
#define all(a) (a).begin(), (a).end()
#define show(x)  cerr << #x << " = " << (x) << endl;
#define debug(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << endl;
const int INF = 2000000000;
using namespace std;


//????????±?????¨??????
const int MAX_N = 1000;
int dp[MAX_N + 1][MAX_N + 1];

int solve(string s, string t, int n, int m){
    rep(i,n){
        rep(j,m){
            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]);
            }
        }
    }
    return dp[n][m];
}

int main(){
    int n;
    string s, t;
    cin >> n;
    rep(i,n){
        cin >> s >> t;
        cout << solve(s, t, s.size(), t.size()) << endl;
    }
}

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

int dp[1000+1][1000+1];

int main() {
    int n; cin >> n;
    while(n--) {
        string s, t; cin >> s >> t;
        int N = s.length();
        int M = t.length();
        dp[0][0] = 0;
        for(int i = 0; i < N; i++) {
            for(int j = 0; j < M; 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]);
            }
        }
        cout << dp[N][M] << endl;
    }
}