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<iostream>
#include<string>
#include<algorithm>
using namespace std;

int lcs(string str1, string str2) {
	int n1 = str1.size();
	int n2 = str2.size();
	int A[n1 + 1][n2 + 1];
	for (int i = 1; i <= n1; i++) A[i][0] = 0;
	for (int j = 1; j <= n1; j++) A[0][j] = 0;

	for (int i = 1; i <= n1; i++) {
		for (int j = 1; j <= n2; j++) { 
			if (str1[i - 1] == str2[j - 1]) {
				A[i][j] = A[i - 1][j - 1] + 1; //?????´??????+1????????¨???????????¨???????????\??????i-1, j-1????????´??°???i,j?????????????????????+1????????¨???????????¨i-1,j??¨?????§?????????????????¶??????
			} else {
				A[i][j] = max(A[i - 1][j], A[i][j - 1]); //?????´?????????????????§i,j??????????????? i-1,j??¨i,j-1
			}
		}
	}
	return A[n1][n2];
}

int main() {
	int n;
	string str1, str2;
	cin >> n;
	for (int i = 0; i < n; i++) {
		cin >> str1 >> str2;
		cout << lcs(str1, str2) << endl;
	}
	return 0;
}

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++) 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]);
    	}
           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<iostream>
#include<string>
using namespace std;

int lcs(string a, string b){
    int i,j,m,n,mx=0;
    m=a.length();
    n=b.length();
    int c[m+1][n+1];
  
    
    for(i=0;i<m+1;i++) c[i][0]=0;
    for(i=0;i<n+1;i++) c[0][i]=0;
    
    for(i=1;i<m+1;i++){
        for(j=1;j<n+1;j++){
            if(a[i-1]==b[j-1]) c[i][j]=c[i-1][j-1] + 1;
            else c[i][j]= max(c[i][j-1],c[i-1][j]);
          	mx = max(mx,c[i][j]);
        }
    }
  return mx;  
}

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

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

#define MAX 1000

int lcs(string X, string Y) {
    int c[MAX+1][MAX+1];
    int m = X.size();
    int n = Y.size();
    int i, j;
    int maxlen = 0;
    X = " " + X;
    Y = " " + Y;

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

    for(i = 1 ; i <= m ; i++ ) {
        for(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]);
            }
            maxlen = max(maxlen, c[i][j]);
        }
    }
    return maxlen;
}

int main (void) {
    int N, i;
    string x, y;

    cin >> N;

    for(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 <algorithm>
#include <queue>

#define rep(i, n) for(int i = 0; i < (int)(n); i++)

using namespace std;

void solve(string s1, string s2) {
    vector<vector<int> > dp(s1.size()+1, vector<int>(s2.size()+1,0));
    rep(i, s1.size()+1) {
        rep(j, s2.size()+1) {
            if(i == 0 || j == 0)
                continue;
            if(s1[i-1] == s2[j-1]){
                dp[i][j] = dp[i-1][j-1]+1;
            }
            else {
                dp[i][j] = max(dp[i-1][j], dp[i][j-1]);
            }
        }
    }
    cout << dp[s1.size()][s2.size()] << endl;
    return;
}

int main(){
    int n; cin >> n;
    string s1,s2;
    rep(i, n) {
        cin >> s1 >> s2;
        solve(s1,s2);
    }
}

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=0;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]);
      }
      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 <iostream>
#include <algorithm>
#include <string>
#include <vector>
using namespace std;

int q;
string X,Y;
int L[1001][1001];

int max(int i,int j) {return i > j ? i : j;}

int getL(int i,int j) {
	if(L[i][j] != -1) return L[i][j];

	if(i == 0 || j == 0) return 0;
	if(X[i - 1] == Y[j - 1]) return 1 + getL(i - 1,j - 1);
	return max(getL(i,j - 1),getL(i - 1,j));
}

int main() {

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

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

int main() {
  std::ios::sync_with_stdio(false);
  cout.tie(0);
  cin.tie(0);
  int N;
  cin>>N;
  string S1,S2;
  for (int k=0; k<N; k++) {
    cin>>S1>>S2;
    int m=S1.length();
    int n=S2.length();
    S1=' '+S1;
    S2=' '+S2;
    int lcs[1001][1001];
    for (int i=1; i<=m; i++) {
      lcs[i][0]=0;
    }
    for (int j=1; j<=n; j++) {
      lcs[0][j]=0;
    }
    int maxl=0;
    for (int i=1; i<=m; i++) {
      for (int j=1; j<=n; j++) {
        if (S1[i]==S2[j]) {
          lcs[i][j]=lcs[i-1][j-1]+1;
        }
        else {
          lcs[i][j]=max(lcs[i-1][j],lcs[i][j-1]);
        }
        maxl=max(maxl,lcs[i][j]);
      }
    }
    cout<<maxl<<endl;
  }
  return 0;
}

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

int lcs(string Xtw,string Ytw){
    int c[N+1][N+1];
    int m=Xtw.size();
    int n=Ytw.size();
    int maxl=0;
    Xtw=' '+Xtw;
    Ytw=' '+Ytw;
    for(int i=0;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(Xtw[i]==Ytw[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 s1tw,s2tw;
    int n; cin>>n;
    for(int i=0;i<n;i++){
        cin>>s1tw>>s2tw;
        cout<<lcs(s1tw,s2tw)<<endl;
    }
    return 0;
}