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

int dp[1005][1005];

int main(){
    int q;
    cin>>q;
    while(q--){
        string s,t;
        cin>>s>>t;
        for(int i=0; i<1005; ++i){
            for(int j=0; j<1005; ++j){
                dp[i][j]=0;
            }
        }
        for(int i=0; i<s.size(); ++i){
            for(int j=0; j<t.size(); ++j){
                if(s[i]==t[j]){
                    dp[i+1][j+1]=max(dp[i+1][j+1],dp[i][j]+1);
                }
                dp[i+1][j+1]=max(dp[i+1][j+1],dp[i][j+1]);
                dp[i+1][j+1]=max(dp[i+1][j+1],dp[i+1][j]);
            }
        }
        cout<<dp[s.size()][t.size()]<<endl;
    }
}

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

static const int N = 1000;

int lcs(string X,string Y){
    int c[N+1][N+1];    //c[i][k]???Xi??¨Yk???LCS??¨??????????????????
    int m = X.size();
    int n = Y.size();
    int maxl = 0;
    X = ' ' + X; // X[0]?????????????????\
    Y = ' ' + Y;
    for(int i=1;i<=m;i++) c[i][0] = 0;
    for(int k=1;k<=n;k++) c[0][k] = 0;

    for(int i=1;i<=m;i++){
        for(int k=1;k<=n;k++){
            if(X[i]==Y[k]){
                c[i][k] = c[i-1][k-1] + 1;
            } else {
                c[i][k] = max(c[i-1][k],c[i][k-1]);
            }
            maxl = max(maxl,c[i][k]);
        }
    }

    return maxl;
}

int main(){
    string s1,s2;
    int n; cin >> n;
    for(int i=0;i<n;i++){
        cin >> s1 >> s2;
        cout << lcs(s1,s2) << endl;
    }

    return 0;
}

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

const static int MAX = 1001;
std::string X, Y;
int LCS[MAX][MAX];

int main(void){
    int q, x_size, y_size;
    std::cin >> q;
    for(int i = 0; i < q; i++){
	std::cin >> X >> Y;
	LCS[0][0] = 0;
	LCS[0][1] = 0;
	LCS[1][0] = 0;
	x_size = X.size();
	y_size = Y.size();
	for(int j = 0; j < X.size(); j++){
	    for(int k = 0; k < Y.size(); k++){
		if(X[j] == Y[k]){
		    LCS[j+1][k+1] = LCS[j][k] + 1;
		}else if(X[j] != Y[k]){
		    LCS[j+1][k+1] = std::max(LCS[j][k+1], LCS[j+1][k]);
		}
	    }
	}
	std::cout << LCS[x_size][y_size] << std::endl;
    }

    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define ll long long
#define vl vector<ll>
#define pl pair<ll,ll>
#define rep(i,b) for(ll i=0;i<b;i++)
#define all(v) (v).begin(),(v).end()

ll lcs(string X,string Y){
    ll c[1001][1001];
    ll m=X.size();
    ll n=Y.size();
    ll maxl=0;
    X=' '+X;
    Y=' '+Y;
    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=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(maxl,c[i][j]);
        }
    }
    return maxl;
}

int main() {
string s1,s2;
ll n;cin>>n;
rep(i,n){
    cin>>s1>>s2;
    cout<<lcs(s1,s2)<<endl;
}
}

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

static int N=1000;

int lcs(string x,string y){
  int num[N+5][N+5];
  int ans=0;
  int leng_x=x.size();
  int leng_y=y.size();  
  
  x=' '+x;
  y=' '+y;

  for(int i=1;i<=leng_x;i++)num[i][0]=0;
  for(int i=1;i<=leng_y;i++)num[0][i]=0;
  

  for(int i=1;i<=leng_x;i++){
    for(int j=1;j<=leng_y;j++){
      if(x[i]==y[j]) num[i][j]=num[i-1][j-1]+1;
      else num[i][j]=max(num[i][j-1],num[i-1][j]);
      ans=max(ans,num[i][j]);
    }
  }
  return ans;
}

int main(){
  string s1,s2;
  int q;

  cin>>q;
  for(int i=0;i<q;i++){
    cin>>s1>>s2;
    cout<<lcs(s1,s2)<<endl;
  }

  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
inline void chmax (int& a, int b) {
  if (a < b) a = b;
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int q;
  cin >> q;
  while (q--) {
    string x, y;
    cin >> x >> y;
    int m = x.length();
    int n = y.length();
    vector<int> dp(n + 1, 0);
    for (int i = 1; i <= m; i++) {
      for (int j = 1; j <= n; j++) {
        chmax(dp[j], dp[j - 1]);
        if (x[i - 1] == y[j - 1]) dp[j] = dp[j - 1] + 1;
      }
    }
    int ret = dp[n];
    cout << ret << '\n';
  }
  return 0;
}