Go: package main

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

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	n, err := nextInt(sc)
	if err != nil {
		panic(err)
	}
	for i := 0; i < n; i++ {
		strX := nextText(sc)
		strY := nextText(sc)
		fmt.Println(calcLcs(strX, strY))
	}
}

func calcLcs(strX, strY string) int {
	lenX, lenY := len(strX), len(strY)
	memo := make([][]int, lenX+1)
	for i := 0; i < lenX+1; i++ {
		memo[i] = make([]int, lenY+1)
	}

	lcs := 0
	for i := 1; i < lenX+1; i++ {
		for j := 1; j < lenY+1; j++ {
			if strX[i-1] == strY[j-1] {
				memo[i][j] = memo[i-1][j-1] + 1
			} else {
				if memo[i-1][j] > memo[i][j-1] {
					memo[i][j] = memo[i-1][j]
				} else {
					memo[i][j] = memo[i][j-1]
				}
			}
			if memo[i][j] > lcs {
				lcs = memo[i][j]
			}
		}
	}
	return lcs
}

func nextInt(sc *bufio.Scanner) (int, error) {
	sc.Scan()
	return strconv.Atoi(sc.Text())
}

func nextText(sc *bufio.Scanner) string {
	sc.Scan()
	return sc.Text()
}

C++: #include<math.h>
#include<limits.h>
#include<iostream>
#include<string>
#include<vector>
#include<stdio.h>
#include<sstream>
#include<list>
#include<queue>
#include<algorithm>
#include<functional>
#include<map>
#include<set>
#include<utility>
#include<initializer_list>
#include<tuple>
#include<regex>
using namespace std;
#define ull unsigned long long
#define ll long long
#define rep(i, n) for(int i=0;i<(int)(n);i++)
#define all(t) t.begin(), t.end()
bool isSubstring(string substr, string t) {
	int n = substr.length();
	int seek = 0;
	rep(i, n) {
		bool ex = 0;
		for (int j = seek; j < t.length(); j++) {
			if (substr[i] == t[j]) {
				ex = 1;
				seek = j + 1;
				break;
			}
		}
		if (ex) {
			continue;
		}
		else {
			return false;
		}
	}
	return true;

}

int LongestCommonSubstring(string s, string t) {
	vector<int>dp(s.length(), 0);
	int n = s.length();
	string lcs = "";
	if (isSubstring(s.substr(n - 1, n), t)) {

		dp[n - 1] = 1;
		lcs = s[n - 1];
	}
	for (int i = n - 2; i >= 0; i--) {
		//string substr = s.substr(i, n);
		string substr = s[i] + lcs;
		int issubst = isSubstring(substr, t);
		if (issubst) lcs = substr;
		dp[i] = dp[i + 1] + issubst;
	}
	return dp[0];
}
int main() {
	//cout << isSubstring("abc", "abcde") << endl;
	//cout << isSubstring("bd", "abcde") << endl;
	//cout << isSubstring("db", "abcde") << endl;

	//cout << LongestCommonSubstring("bacd", "becd") << endl;
	//cout << LongestCommonSubstring("abcd", "becd") << endl;
	int q;
	cin >> q;
	vector<string> s(q);
	vector<string> t(q);
	rep(i, q) {
		cin >> s[i] >> t[i];
	}
	rep(i, q) {
		cout << LongestCommonSubstring(s[i], t[i]) << endl;
	}

	return 0;
}

C++: #include <iostream>
#include <cstring>
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.h>
#include<algorithm>

#define MAX 100

using namespace std;

int lcs(string s1, string s2) {
    int C[MAX+1][MAX+1];
    int m = s1.size();
    int n = s2.size();
    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 (s1[i-1] == s2[j-1]) {
                C[i][j] = C[i-1][j-1] + 1;
            }
            else {
                C[i][j] = max(C[i][j-1], C[i-1][j]);
            }
        }
    }

    return C[m][n];
}

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

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

// ???????????§???????????§?????§??????
// int L[1024][1024] = {};

int main(){
    int N;
    cin >> N;
    for(int c=0; c<N; ++c){
        string X,Y;
        cin >> X >> Y;
        int xlen = (int)X.size();
        int ylen = (int)Y.size();

        // vector??§??????
        vector<vector<int> > L(xlen+1 ,vector<int>(ylen+1, 0));

        for(int i=0;i<=xlen;++i){
          L[i][0] = 0;
        }
        for(int i=0;i<=ylen;++i){
          L[0][i] = 0;
        }

        for(int i=1;i<=xlen;++i){
            for(int j=1;j<=ylen;++j){
                if(X[i-1] == Y[j-1]){ // X???i???????????¨Y???j?????????????????????????????????index?????????????????¨?????¨??????
                    L[i][j] = L[i-1][j-1] + 1;
                } else {
                    L[i][j] = max(L[i-1][j], L[i][j-1]);
                }
            }
        }
        cout << L[xlen][ylen] << endl;
    }
}

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; //x[0]
    y = ' ' + y; //y[0]
    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 <string>
#include <vector>
using namespace std;

#define MAX(a,b) ((a)>(b)?(a):(b))

int LCS(string& wordA, string& wordB) {
	int i,j;
	int sizeA, sizeB;
	vector<vector<int> > lcs;
	sizeA=(int)wordA.size();
	sizeB=(int)wordB.size();
	lcs.resize(sizeA+1);
	lcs[0].resize(sizeB+1);
	for(i=0; i<=sizeB; ++i) {
		lcs[0][i]=0;
	}
	for(i=1; i<=sizeA; ++i) {
		lcs[i].resize(sizeB+1);
		lcs[i][0]=0;
		for(j=1; j<=sizeB; ++j) {
			if(wordA[i-1]==wordB[j-1]) lcs[i][j]=lcs[i-1][j-1]+1;
			else lcs[i][j]=MAX(lcs[i-1][j],lcs[i][j-1]);
		}
	}
	return lcs[sizeA][sizeB];
}

int main() {
	int i,j,k,q;
	cin >> q;
	string wordA,wordB;
	for(i=0; i<q; ++i) {
		cin >> wordA >> wordB;
		cout << LCS(wordA, wordB) << endl;
	}
	return 0;
}

C++: #include<iostream>
#include<string>
int main()
{
  int n;
  int an[1000];
  int l=0;
  std::cin>>n;
  std::string x;
  std::string y;
  int ans[100000][100000];
  int j,k;
  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++){
	ans[j][k]=0;
      }
    }
    for(int j=0;j<x.size();j++){
      for(int k=0;k<y.size();k++){
	if(x[j]==y[k]){
	  ans[j][k]=ans[j-1][k-1]+1;
	}else{
	  if(ans[j][k-1]>ans[j-1][k]){
	    ans[j][k]=ans[j][k-1];
	  }else{
	    ans[j][k]=ans[j-1][k];
	  }
	}
      }
    }
    std::cout<<ans[x.size()-1][y.size()-1]<<'\n';  
  }
  return 0;
}