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 <vector>
using namespace  std;

void fnInput(vector<string>& rvsStrX, vector<string>& rvsStrY)
{
  int nMaxSiz;
  cin >> nMaxSiz;
  rvsStrX.resize(nMaxSiz);
  rvsStrY.resize(nMaxSiz);

  for (int i = 0; i < nMaxSiz; ++i)
  {
    cin >> rvsStrX[i] >> rvsStrY[i];
    rvsStrX[i] = ' ' + rvsStrX[i];
    rvsStrY[i] = ' ' + rvsStrY[i];
  }
}

int fnLngCmnSubseq(const vector<string>& cnrvsStrX, const vector<string>& cnrvsStrY)
{
  for (int i = 0; i < cnrvsStrX.size(); ++i)
  {
    const int nMAXNX = cnrvsStrX[i].size();
    const int nMAXNY = cnrvsStrY[i].size();
    vector<vector<int>> vvnLcsDP(nMAXNX, vector<int>(nMAXNY, 0));

    for (int nx = 1; nx < nMAXNX; ++nx)
      for (int ny = 1; ny < nMAXNY; ++ny)
        if (cnrvsStrX[i][nx] == cnrvsStrY[i][ny])
          vvnLcsDP[nx][ny] = vvnLcsDP[nx - 1][ny - 1] + 1;
        else
          vvnLcsDP[nx][ny] = max(vvnLcsDP[nx - 1][ny], vvnLcsDP[nx][ny - 1]);

    cout << vvnLcsDP[nMAXNX - 1][nMAXNY - 1] << endl;
  }
}

int main()
{
  cin.tie(0);
  ios::sync_with_stdio(false);
  vector<string> vsStrX, vsStrY;

  fnInput(vsStrX, vsStrY);
  fnLngCmnSubseq(vsStrX, vsStrY);
  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-1] == Y[j-1]) {
				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 <iostream>
#include <string.h>
#include <algorithm>
#define MAX 1000

using namespace std;

string s,t;
int dp[MAX + 1][MAX + 1];

int LCS(void){

  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] = dp[i][j] + 1;
      }else{
	dp[i + 1][j + 1] = max( dp[i + 1][j] , dp[i][j + 1]);
      }
    }
  }
  return dp[s.size()][t.size()];
}


int main(void){

  int n;
  cin >> n;
  while(n--){

    memset(dp, 0 , sizeof(dp) );

    cin >> s >> t;
    cout << LCS() << endl;

  }
  return 0;
}

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

int lcs( string X , string Y) {
int c[ N + 1 ][ N + 1 ] ; 
int m = X.size() ; 
int n = Y.size() ; 
int max1 = 0 ;
X = ' ' + X[0] ;
Y = ' ' + Y[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]);
       }
       max1 = max(max1, c[i][j] ) ;
     }
   }
 return max1 ;
}

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 <string>

using namespace std;

// 多次元配列の初期化方法確認
// 出力確認
//
void traceback (string x, string y, vector<vector<int>> L) {
	string lcs;
	int i = x.length();
	int j = y.length();
	while(i != 0 && j != 0) {
		if (L[i][j] == L[i-1][j-1] + 1) {
			lcs = x[i-1] + lcs;
			i--;
			j--;
		} else if (L[i][j-1] >= L[i-1][j]) {
			j--;
		} else if (L[i][j-1] <= L[i-1][j]) {
			i--;
		}
	}
	
	cout << lcs << endl;
}

int main(void) {
	int q;
	cin >> q;
	string x, y;
	
	while(q--) {
		cin >> x >> y;

	//	vector<vector<int>> L(max(x.length(), y.length()), 0);
		vector<vector<int>> L(x.length() + 1, vector<int>(y.length() + 1, 0));
		for (int i = 0; i <= x.length(); i++) {
			for (int j = 0; j <= y.length(); j++) {
				if (i == 0 || j == 0) L[i][j] = 0;
				else if (x[i-1] == y[j-1]) {
					L[i][j] = L[i-1][j-1] + 1;
				} else if (x[i-1] != y[j-1]) {
					L[i][j] = max(L[i-1][j], L[i][j-1]);
				}
			}
		}
		//出力がよくない状況
		cout << L[x.length()][y.length()] << endl;

		//traceback(x, y, L);
	}

}
// xi = yj
// Lij = Li-1j-1 + 1
// Lij = max(Li-1j, Lij-1)

C++: #include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)



int lcs(string X,string Y){
	int dp[1001][1001];
  	int maxl=0; 
  	int m=X.size();int n=Y.size();
  	rep(i,m+1){dp[i][0]=0;}
  	rep(i,n+1){dp[0][i]=0;}
  	X=' '+X;Y=' '+Y;
  	for(int i=1;i<=m;i++){
    	for(int j=1;j<=n;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]);
            }   
          maxl=max(maxl,dp[i][j]);
          
        }
    } 
  return maxl;
}

int main() {
	int q;
  	cin >>q;
  	rep(k,q){
    	string x,y;
    	cin >>x>>y;
      	cout <<lcs(x,y)<<endl;
      	
    }  
}