Go: package main

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

// I/O
type Scanner struct {
	sc *bufio.Scanner
}

func NewScanner() *Scanner {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	sc.Buffer(make([]byte, 1024), int(1e+9))
	return &Scanner{sc}
}

func (s *Scanner) nextStr() string {
	s.sc.Scan()
	return s.sc.Text()
}

func (s *Scanner) nextInt() int {
	i, e := strconv.Atoi(s.nextStr())
	if e != nil {
		panic(e)
	}
	return i
}

func (s *Scanner) nextFloat() float64 {
	f, e := strconv.ParseFloat(s.nextStr(), 64)
	if e != nil {
		panic(e)
	}
	return f
}

func (s *Scanner) nextRuneSlice() []rune {
	return []rune(s.nextStr())
}

func (s *Scanner) nextIntSlice(n int) []int {
	res := make([]int, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextInt()
	}
	return res
}

func (s *Scanner) nextFloatSlice(n int) []float64 {
	res := make([]float64, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextFloat()
	}
	return res
}

// Arithmetic
func max(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m < i {
			m = i
		}
	}
	return m
}

func min(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m > i {
			m = i
		}
	}
	return m
}

func abs(x int) int {
	if x > 0 {
		return x
	}
	return -x
}

func pow(x, y int) int {
	res := 1
	for i := 0; i < y; i++ {
		res *= x
	}
	return res
}

func ceil(a, b int) int {
	if a%b == 0 {
		return a / b
	} else {
		return a/b + 1
	}
}

// Sort
type RuneSlice []rune

func (a RuneSlice) Len() int           { return len(a) }
func (a RuneSlice) Less(i, j int) bool { return a[i] < a[j] }
func (a RuneSlice) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }

// Main
func main() {
	sc := NewScanner()
	wtr := bufio.NewWriter(os.Stdout)
	Q := sc.nextInt()
	for q := 0; q < Q; q++ {
		X, Y := sc.nextStr(), sc.nextStr()
		xLen, yLen := len(X), len(Y)
		dp := make([][]int, xLen+1)
		for i := 0; i <= xLen; i++ {
			dp[i] = make([]int, yLen+1)
		}
		for x := 0; x <= xLen; x++ {
			for y := 0; y <= yLen; y++ {
				if x == 0 || y == 0 {
					dp[x][y] = 0
				} else if X[x-1] == Y[y-1] {
					dp[x][y] = dp[x-1][y-1] + 1
				} else {
					dp[x][y] = max(dp[x-1][y], dp[x][y-1])
				}
			}
		}
		fmt.Fprintln(wtr, dp[xLen][yLen])
	}

	wtr.Flush()
}

C++: #include <iostream>
#include <climits>
#include <string>
using namespace std;
const int MAXSEQ = 1000;
const int INFY = -INT_MAX;

string X, Y;

int max(int m, int n){
    int max = INFY;
    printf("\n");
    return max;
}
int LSCLength(void){
    int m = X.size();
    int n = Y.size();
    int c[m+1][n+1];
    for (int i = 0; i <= m; i++){
        c[i][0] = 0;
    }
    for (int j = 0; j <= n; j++){
        c[0][j] = 0;
    }
    /*
    for (int i = 0; i <= m; i++){
        for (int j = 0; j <= m; j++){
        */
    /*
    if (m > n){
        cout << "will change X =" <<  X << endl;
        swap(m, n);
        swap(X, Y);
        cout << "changed X =" <<  X << endl;
    }*/
    for (int i = 1; i <= m; i++){
        for (int j = 1; j <= n; j++){
            if (X[i-1] == Y[j-1]){
                c[i][j] = c[i-1][j-1] + 1;
            }else if (c[i-1][j] >= c[i][j-1]){
                c[i][j] = c[i-1][j];
            }else{
                c[i][j] = c[i][j-1];
            }
        }
    }
    int max = INFY;
    //printf("\n");
    /*
    for (int i = 0; i <= m; i++){
        for (int j = 0; j <= n; j++){
            printf("%d ", c[i][j]);
        if (max < c[m][i]) max = c[i][j];
        }
        printf("\n");
    }
    */
    for (int j = 1; j <= n; j++){
        if (max < c[m][j]) max = c[m][j];
    }
    return max;
}

int main(int argc, char* argv[]) {
    int n;
    cin >> n;
    for (int i = 0; i < n; i++){
        cin >> X >> Y;
        cout << LSCLength() << endl;
    }
    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define FOR(I,A,B) for(ll I = (A); I < (B); ++I)
#define POSL(x,v) (lower_bound(x.begin(),x.end(),v)-x.begin()) //xi>=v
#define POSU(x,v) (upper_bound(x.begin(),x.end(),v)-x.begin()) //xi>v
#define NUM(x,v) (POSU(x,v)-POSL(x,v))
const ll INF=1e9+7;
const ll N = 1002;
const ll M = 21;
ll q,dp[N][N];
string x,y;
vector <ll> ans;

int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);
	cin>>q;
	FOR(k,0,q){
		cin>>x>>y;
		FOR(i,0,x.size()+1){
			FOR(j,0,y.size()+1){
				dp[i][j]=0;
			}
		}
		FOR(i,0,x.size()+1){
			FOR(j,0,y.size()+1){
				if(i==0||j==0)dp[i][j]=0;
				else{
					if(x[i]==y[j])dp[i][j] = max(dp[i-1][j]+1,dp[i][j-1]+1);
					else dp[i][j] = max(dp[i-1][j],dp[i][j-1]);
				} 
			}
		}
		ans.push_back(dp[x.size()][y.size()]);
	}
	FOR(i,0,ans.size()){
		cout<<ans[i]<<endl;
	}
	return 0;
}

C++: #include <bits/stdc++.h>
#define INF 10000
using namespace std;

int main(){
  int N; cin>>N;
  for (int i =0; i<N; i++) {
    string s1,s2; cin >> s1 >> s2;
    int s1N = s1.size();
    int s2N = s2.size();
    int dp[s1N+1][s2N+1];
    
    for(int j=0; j<=s1N; j++) dp[j][0] =0;
    for(int k=0; k<=s2N; k++) dp[0][k] =0;
  
    for(int j=1; j<=s1N; j++){
      for(int k=1; k<=s2N; k++){ 
        if(s1[j-1] == s2[k-1]) {
          dp[j][k] = dp[j-1][k-1] +1;
        } else {
          dp[j][k] = max(dp[j][k-1], dp[j-1][k]);
        }
      }
    }
    cout << dp[s1N][s2N] <<endl; 
  }
}

C++: #include <iostream>
#include <algorithm>
#include <cstdio>
#include <cmath>
#include <string>
#include <cctype>
#include <stack>
#include <queue>
#include <vector>
#include <cstdlib>
#include <list>
#define _USE_MATH_DEFINES
#include <math.h>

using namespace std;

int lcs(string X, string Y) {
	int n, m;
	int c[1001][1001] = { 0 };
	int maxlcs = 0;;

	m = X.size();
	n = Y.size();


	X = ' ' + X;
	Y = ' ' + Y;

	for (int i = 1; i <= m; i++)c[i][0] = 0;
	for (int j = 1; j <= n; j++)c[0][j] = 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][j - 1],c[i - 1][j]);

			maxlcs = max(maxlcs, c[i][j]);
		}
	}
	return maxlcs;
}

int main() {

	int n;
	string S1, S2;

	cin >> n;
	for (int i = 0; i < n; i++) {
		cin >> S1 >> S2;
		cout << lcs(S1, S2) << endl;
	}

	return 0;
}

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

string X, Y;
int v[1001][1001];

int  dp(string X, string Y) {
	int n = X.size();
	int m = Y.size();

	for (int i = 0; i < n; i++) {
		v[i][0] = 0;											///０のテーブル
		for (int j = 0; j < m; j++) {
			v[0][j] = 0;
		}
	}

	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= m; j++) {
			if (X[i] == Y[j]) {
				v[i][j] = v[i - 1][j - 1] + 1;
			}
			else {
				v[i][j] = max(v[i - 1][j], v[i][j - 1]);
			}
		}
	}
	return v[n][m];
}

int main(void)
{
	int x;
	cin >> x;

	for (int i = 0; i < x; i++) {
		cin >> X >> Y;
		int ans = dp(X, Y);
		cout << ans << endl;
	}
}

C++: #include<bits/stdc++.h>
#define dump(a) cout << #a << " " << a << endl
#define MAX_SIZE 1000
using namespace std;

string X,Y;
int dp[MAX_SIZE+1][MAX_SIZE+1];

int dfs(int xi, int yi) {
	if (dp[xi][yi] != -1) { return dp[xi][yi]; }

	if (xi==X.size() || yi==Y.size()) { return 0; }
	else if (X[xi] == Y[yi]) {
		dp[xi][yi] = dfs(xi+1,yi+1) + 1;
	}
	else {
		dp[xi][yi] = max(dfs(xi,yi+1),dfs(xi+1,yi));
	}
	return dp[xi][yi];
}

int main() {
	int N;

	cin >> N;

	for(int i=0; i<N; i++) {
		cin >> X >> Y;
		memset(dp,-1,sizeof(dp)); //-1??§?????????
		cout << dfs(0,0) << endl;
	}

	return EXIT_SUCCESS;
}