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<iomanip>
#include<cmath>
#include<string>
#include<vector>
#include<list>
#include<algorithm>
#include<map>
#include<set>
#include<queue>
#include<stack>
using namespace std;
typedef long long ll;
#define fi first
#define se second
#define mp make_pair
#define rep(i, n) for(int i=0;i<n;++i)
#define rrep(i, n) for(int i=n;i>=0;--i)
const int inf=1e9+7;
const ll mod=1e9+7;
const ll big=1e18;
const double PI=2*asin(1);

int DP[1005][1005];

int main() {
    int N;
    cin>>N;
    string S, T;
    int ans[N];
    for(int i=0;i<N;++i){
        cin>>S>>T;
        for(int j=0;j<S.size();++j){
            for(int k=0;k<T.size();++k){
                DP[j][k] = 0;
            }
        }
        if(S[0]==T[0]) DP[0][0] = 1;
        for(int j=1;j<S.size();++j){
            if(S[j]==T[0]) DP[j][0] = 1;
            DP[j][0] = max(DP[j-1][0], DP[j][0]);
        }
        for(int j=1;j<T.size();++j){
            if(S[0]==T[j]) DP[0][j] = 1;
            DP[0][j] = max(DP[0][j-1], DP[0][j]);
        }
        for(int j=1;j<S.size();++j){
            for(int k=1;k<T.size();++k){
                if(S[j]==T[k]) DP[j][k] = DP[j-1][k-1] + 1;
                else DP[j][k] = max(DP[j-1][k], DP[j][k-1]);
            }
        }
        ans[i] = DP[S.size()-1][T.size()-1];
    }
    for(int i=0;i<N;++i){
        cout<<ans[i]<<endl;
    }
}

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

using namespace std;

int lcs(string a, string b)
{
	vector<vector<int> > dp(1001, vector<int>(1001));
	for (int i = 0; i < a.size(); ++i)
	{
		for (int j = 0; j < b.size(); ++j)
		{
			if (a[i] == b[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[a.size()][b.size()]);
}

void solve()
{
	int q;
	cin >> q;
	for (int i = 0; i < q; ++i)
	{
		string a, b;
		cin >> a >> b;
		cout << lcs(a, b) << endl;
	}
}

int main()
{
	solve();
	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++){
    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 <cstring>
#include <algorithm>
#include <queue>
#include <cstdio>
#include <cstdlib>
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; //X[0]に空白を挿入
    Y = ' ' + Y; //Y[0]に空白を挿入

    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() {

    int n;
    cin >> n;

    string a, b;

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

C++: #include<iostream>

int main(){
  int n;
  std::string x,y;
  std::cin>>n;
  int a[1000][1000];

  for(int i=0;i<n;i++){
    std::cin>>x;
    std::cin>>y;
    for(int j=0;j<1000;j++){
      for(int k=0;k<1000;k++){
	a[j][k]=0;
      }
    }
    for(int j=0;j<x.size();j++){
      for(int k=0;k<y.size();k++){
	if(x[j]==y[k]){
	  a[j][k]=a[j-1][k-1]+1;
	}else{
	  if(a[j-1][k]>a[j][k-1]){
	    a[j][k]=a[j-1][k];
	  }else{
	    a[j][k]=a[j][k-1];
	  }
	}
      }
    }
    std::cout<<a[x.size()-1][y.size()-1]<<"\n";
  }
  return 0;
}

C++: #include <iostream>
#include <string>
#include <map>
#include <vector>

using std::cin;
using std::cout;
using std::cerr;
using std::endl;

// 最長共通部分列 ... len(s) == m, len(t) == n とすると, O(mn)
int lcs(std::string s, std::string t) {
  std::vector<std::vector<int> > dp(s.size() + 1, std::vector<int>(t.size() + 1, 0));

  for (int i = 1; i <= s.size(); ++i) {
    for (int j = 1; j <= t.size(); ++j) {
      if (s[i - 1] == t[j - 1]) {
        dp[i][j] = dp[i - 1][j - 1] + 1;
      }
      else if (dp[i - 1][j] >= dp[i][j - 1]) {
        dp[i][j] = dp[i - 1][j];
      }
      else {
        dp[i][j] = dp[i][j - 1];
      }
    }
  }

  return dp[s.size()][t.size()];
}

int main() {
  int q;
  std::string s, t;
  cin >> q;
  for (int i = 0; i < q; ++i) {
    cin >> s >> t;
    cout << lcs(s, t) << endl;
  }

  return 0;
}

C++: #include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>

using namespace std;
const int maxn=1000+10;
int n;
char a[maxn],b[maxn];
int dp[maxn][maxn];
void solve(char *a,char *b)
{

    int la=strlen(a)-1,lb=strlen(b)-1;
    for(int i=0;i<la;i++) dp[i][0]=0;
    for(int i=0;i<lb;i++) dp[0][i]=0;

    for(int i=0;i<la;i++)
    {
        for(int j=0;j<lb;j++)
        {
            if(a[i]==b[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]);
        }

    }
    printf("%d\n",dp[la][lb]);

}
int main()
{
//    freopen("in.txt","r",stdin);
    scanf("%d",&n);
    getchar();
    while(n--)
    {
        fgets(a,sizeof(a),stdin);
        fgets(b,sizeof(b),stdin);
        solve(a,b);
    }

    return 0;
}

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

int lcs(string x,string y);

int main(){
	int n; cin>>n;
	string x,y;
	for(int i=0;i<n;i++){
		cin>>x>>y;
		cout<<lcs(x,y)<<endl;
	}
	cin.get();cin.get();
}

int lcs(string x,string y){
	int m = x.size() , n = y.size();
	x = ' '+x; y = ' '+y;
	int **c;
	c = new int*[m+1]; for(int i=0;i<=m;i++) c[i] = new int[n+1];
	for(int i=0;i<=m;i++) c[i][0] = 0; for(int j=0;j<=n;j++) c[0][j] = 0;
	int maxl = 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]);
		}
	}
	for(int i=0;i<=m;i++) delete [] c[i]; delete [] c;
	return maxl;
}