Go: package main

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

const (
	initialBufSize = 100000
	maxBufSize     = 1000000
)

var sc *bufio.Scanner

func initScanner(r io.Reader) *bufio.Scanner {
	buf := make([]byte, initialBufSize)

	sc := bufio.NewScanner(r)
	sc.Buffer(buf, maxBufSize)
	sc.Split(bufio.ScanWords) // bufio.ScanLines
	return sc
}

func main() {
	sc = initScanner(os.Stdin)
	resolve()
}

func resolve() {
	n := scanInt(sc)
	results := []int{}
	for i := 0; i < n; i++ {
		results = append(results, resolveInstance())
	}
	for _, v := range results {
		fmt.Println(v)
	}
	return
}

func resolveInstance() int {
	x, y := scanString(sc), scanString(sc)
	lx, ly := len(x), len(y)
	dp := make([][]int, lx+1)
	dp[0] = make([]int, ly+1)
	for i := 1; i <= lx; i++ {
		dp[i] = make([]int, ly+1)
		dp[i][0] = dp[i-1][0]
		for j := 1; j <= ly; j++ {
			dp[i][j] = dp[i-1][j]
			if dp[i][j] < dp[i][j-1] {
				dp[i][j] = dp[i][j-1]
			}
			if x[i-1] == y[j-1] {
				cL := dp[i-1][j-1] + 1
				if dp[i][j] < cL {
					dp[i][j] = cL
				}
			}
		}
	}
	return dp[lx][ly]
}

const (
	remove = 0 + iota
	match
)

// snip-scan-funcs
func scanInt(sc *bufio.Scanner) int {
	sc.Scan()
	i, _ := strconv.Atoi(sc.Text())
	return int(i)
}
func scanString(sc *bufio.Scanner) string {
	sc.Scan()
	return sc.Text()
}

C++: #include <iostream>
#include <string>
#include <algorithm>
using namespace std;
static const int N = 1000;

int lcs ( string X, string Y ) {
	int c[N + 1][N + 1];
	int m = X.size();
	int n = Y.size();
	int maxl = 0;
	X = ' ' + X;
	Y = ' ' + Y;	
	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;
	int n;
	cin >> n;
	for ( int i = 0; i < n; i++ ) {
		cin >> s1 >> s2;
		cout << lcs(s1, s2) << endl;
	}
	return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
static const int N=1001;
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;
  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-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 <cstdio>
#include <string.h>
#include <algorithm>

using namespace std;

typedef long long ll;

int lcs(string X, string Y){
  int x = X.size();
  int y = Y.size();

  int d[y+1][x+1];
  memset(d, 0, sizeof(d));

  for(int i = 1; i <= y; i++){
    char a = Y[i];

    for(int j = 1; j <= x; j++){
      char b = X[j];

      if(a == b){
        d[i][j] = max(d[i][j], d[i-1][j-1] + 1);
      }else{
        d[i][j] = max(d[i][j], max(d[i-1][j], d[i][j-1]));
      }
    }
  }

  return d[y][x];
}

int main(){
  int n;
  string x, y;
  cin >> n;

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

    cout << lcs(x, y) << endl;
  }

  return 0;
}

C++: #include <iostream>
#include <vector>
#include <string>
#include <cmath>
#include <set>
#include <algorithm>
#include <array>
#include <complex>
#include <utility>
#include <map>
#include <inttypes.h>

int LCS(std::string s,std::string t){
    int n,m,c[1001][1001];
    n=s.size();
    m=t.size();
    int maxlen=0;
    for(int i=1;i<=n;i++){
        c[i][0]=0; 
    }
    for(int i=1;i<=m;i++){
        c[0][i]=0;
    }
    for(int i=1;i<=n;i++){
        for(int j=1;j<=m;j++){
            if(s[i]==t[i]){
                c[i][j]=c[i-1][j-1]+1;
            }else{
                c[i][j]=std::max(c[i-1][j],c[i][j-1]);
            }
            maxlen=std::max(c[i][j],maxlen);
        }
    }
    return maxlen;
}
int main(){
	int N;
    
    std::cin >> N;
    std::string s1,s2;
    for(int i=0;i<N;i++){
        std::cin >> s1 >> s2;
        std::cout << LCS(s1,s2) <<std::endl;
    }
        
    
    return 0;
}

C++: #include <stdio.h>
#include <iostream>
#include <algorithm>
#include <vector>
#include <math.h>
#include <string>
#include <string.h>

#define FOR(i,a,b) for (int i=(a);i<(b);i++)
#define RFOR(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define REP(i,n) for (int i=0;i<(n);i++)
#define RREP(i,n) for (int i=(n)-1;i>=0;i--)

using namespace std;
int dp[1001][1001];
//?????????????????????
int n;
string x,y;
void solve(){
	cin >> n;
	REP(j,n){
	cin >> x >> y;
	memset(dp,0,1001*1001);
	int xn = x.size();
	int yn = y.size();
	REP(jj,xn+1){
		 REP(ii,yn+1){
			 if(jj <= 0 || ii <= 0){
				 dp[jj][ii] = 0 ;
			 }
			 else if(x[jj-1]==y[ii-1]) {
				 dp[jj][ii] = 1 + dp[jj-1][ii-1];
			 }
			 else{
				 dp[jj][ii] = max ( dp[jj-1][ii], dp[jj][ii-1] );
		   }
			 //cout << '('<<ii<<','<<jj<<')'<<dp[jj][ii]<<endl;
		 }

	}
	cout << dp[xn][yn]<<endl;
	}


}


int main(){
solve();
}

C++: #include <iostream>

using namespace std;

int lcs(string X, string Y) {
  int memo[1010][1010];
  int maxl = 0;

  for (int i = 0; i < X.size(); i++) {
    for (int j = 0; j < Y.size(); j++) {
      if (X[i] == Y[j]) {
        if (i == 0 || j == 0) {
          memo[i][j] = 1;
        } else {
          memo[i][j] = memo[i-1][j-1] + 1;
        }
      } else {
        if (i == 0 || j == 0) {
          memo[i][j] = 0;
        } else {
          memo[i][j] = max(memo[i-1][j], memo[i][j-1]);
        }
      }
      maxl = max(maxl, memo[i][j]);
      //cout << i << "," << j << "," << X[i] << "," << Y[j] << "," << maxl << endl;
    }
  }
  return maxl;
}

int main() {
  int q; cin >> q;
  for (int i = 0; i < q; i++) {
    string X, Y; cin >> X >> Y;
    cout << lcs(X, Y) << endl;
  }
}

C++: #define _CRT_SECURE_NO_WARNINGS
#define _USE_MATH_DEFINES
//#include "MyMath.h"
//#include "DataStructure.h"
#include <iostream>
#include <vector>
#include <algorithm>
#include <queue>
#include <functional>
#include <stdio.h>
using namespace std;
typedef pair<int, int> p;
const int INF = 1000000000;
int main(){
	int n; cin >> n;
	for (int k = 0; k < n; k++) {
		char s[1000], t[1000];
		scanf("%s",&s); scanf("%s", &t);
		int i = 0, j = 0;
		int dp[1001][1001];
		fill(dp[0], dp[1001], 0);
		int res = 0;
		while (s[i] != '\0'){
			while (t[j] != '\0') 
			{
				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]);
				res = dp[i + 1][j + 1];
				//cout << "i " << i << "j " << j << endl;
				//cout << "dp" << dp[i + 1][j + 1] << endl;
				j++;
			}
			i++;
			j = 0;
		}

		cout << res << endl;
	}
	return 0;
}

C++: #include <iostream>
#include <string>
using namespace std;
int main(){

    string a,b;
    int n,nmax;
    
    cin>>n;
    for(int i=0;i<n;i++){
        int dp[1000]={0},result=0;
        cin>>a>>b;
        for(int j=0;j<a.size();j++) if(b[0]==a[j]) dp[j]++;
        for(int j=1;j<b.size();j++){
            nmax=0;
            if(b[j]==a[0]) dp[0]=1;
            for(int k=1;k<a.size();k++){
                nmax=max(dp[k-1],nmax);
                if(b[j]==a[k]) dp[k]=nmax+1;
            }
        }
        nmax=0;
        for(int j=0;j<a.size();j++) nmax=max(dp[j],nmax);
        cout<<nmax<<endl;
        
    }
    
    return 0;
    
}