Go: package main

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

type Position struct {
	X int
	Y int
}

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 {
	return lcs(strX, strY, Position{0, 0}, make(map[Position]int))
}

func lcs(strX string, strY string, position Position, memo map[Position]int) int {
	if position.X >= len(strX) || position.Y >= len(strY) {
		return 0
	}
	if v, ok := memo[position]; ok {
		return v
	}
	if strX[position.X] == strY[position.Y] {
		result := lcs(strX, strY, Position{position.X + 1, position.Y + 1}, memo)
		memo[position] = result + 1
		return memo[position]
	} else {
		result1 := lcs(strX, strY, Position{position.X + 1, position.Y}, memo)
		result2 := lcs(strX, strY, Position{position.X, position.Y + 1}, memo)
		var result int
		if result1 > result2 {
			result = result1
		} else {
			result = result2
		}
		memo[position] = result
		return result
	}
}

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 <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
const int maxx = 1010;
int c[maxx][maxx];

int lcs(char s1[],char s2[]) {
	int m = strlen(s1), n = strlen(s2);
	for (int i = 1; i <= m; i++)
		c[i][0] = 0;
	for (int i = 1; i <= n; i++)
		c[0][i] = 0;

	for (int i = 1; i <= m; i++) {
		for (int j = 1; j <= n; j++) {
			if (s1[i] == s2[j])
				c[i][j] = c[i - 1][j - 1] + 1;
			else
				c[i][j] = max(c[i - 1][j], c[i][j - 1]);
		}
	}
	return c[m][n];
}
int main()
{
	char s1[maxx], s2[maxx];
	int t;
	scanf("%d", &t);
	for (int i = 0; i < t; i++) {
		scanf("%s %s", s1, s2);
		printf("%d\n", lcs(s1,s2));
	}

	return 0;
}

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

void solve(){
  int q; cin >> q;
  for(int i = 0; i < q; i++){
    string x, y; cin >> x >> y;
    int xn = x.size(), yn = y.size();
    vector<vector<int> > lcs(xn + 1, vector<int>(yn + 1));
    for(int i = 0; i <= xn; i++) lcs[i][0] = 0;
    for(int i = 0; i <= yn; i++) lcs[0][i] = 0;
    for(int j = 1; j <= xn; j++){
      for(int k = 1; k <= yn; k++){
        if(x[j - 1] == y[k - 1]) lcs[j][k] = lcs[j - 1][k - 1] + 1;
        else lcs[j][k] = max(lcs[j - 1][k], lcs[j][k - 1]);
      }
    }
    cout << lcs[xn][yn] << endl;
  }
  return;
}

int main(){
  solve();
  return 0;
}

C++: 

#include <iostream>
#include<string>
#include<algorithm>
using namespace std;
#define LEN  1001
int Position[LEN][LEN];//每个坐标都是LCS的长度
int includeGetLCS(string first, string second)
{
	int firstlen = first.size();
	int secondlen = second.size();//得到string的长度
	first = " " + first, second = " " + second;//在前面加个空格，以便下面；
	int Position[LEN][LEN];//每个坐标都是LCS的长度
	for (int i = 0; i <= secondlen; i++) Position[0][i]=0;//任意一方没有数据，LCS为0；
	for (int i = 1; i <=firstlen; i++)Position[i][0]=0;
	for (int i = 1; i <= firstlen; i++)
	{
		for (int j = 1; j <= secondlen; j++)
		{
			if (first[i] == second[j])//最后一个相等时候
				Position[i][j] = Position[i - 1][j - 1] + 1;//前面的LCS+1；
			else
			{
				if (Position[i][j - 1] >= Position[i - 1][j])//不相等的时候，比较各自减一的LCS，取最大的那个LCS
					Position[i][j] = Position[i][j - 1];
				else
					Position[i][j] = Position[i - 1][j];
			}
		}

	}
int max=0;
	if (max >= Position[firstlen][secondlen])
		return max;
	else
		return	Position[firstlen][secondlen];
}
int main()
{
	string first, second;
	int number;
	cin >> number;
	for (int i = 0; i < number; i++)
	{
		cin >> first>>second;
		cout << includeGetLCS(first, second)<<endl;
	}
}

C++: #include<iostream>
#include<vector>
#include<string>
#include<cstdio>
#include<set>
#include<algorithm>
#define ll long long
using namespace std;

int dp[1001][1001];
int main() {
	int b;
	scanf("%d", &b);
	char e[1001];
	char f[1001];
	for (int c = 0; c < b; c++) {
		scanf("%s%s", e, f);
		for (int g = 0; g <= strlen(e); g++) {
			for (int h = 0; h <= strlen(f); h++) {
				dp[g][h] = 0;
			}
		}
		for (int g = 1; g <= strlen(e); g++) {
			for (int h = 1; h <= strlen(f); h++) {
				if (e[g] == f[h]) {
					dp[g][h] = dp[g - 1][h - 1] + 1;
				}
				else {
					dp[g][h] = max(dp[g][h - 1], dp[g - 1][h]);
				}
			}
		}
		printf("%d\n", dp[strlen(e)][strlen(f)]);
	}
}

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

const int s=1001;

using namespace std;

int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);

	int q;
	static unsigned int dp[s][s] = {0};
	
	dp[0][0] = 0; dp[0][1] = 0; dp[1][0] = 0;

	cin >> q;
	for(int k=0; k < q; k++){
		string X,Y;
		cin >> X >> Y;
		int i,j;
		for(i=0;i<X.size();i++){
			for(j=0;j<Y.size();j++){
				if(X[i] == Y[j]) dp[i+1][j+1] = dp[i][j] + 1;
				else dp[i+1][j+1] = max(dp[i][j+1],dp[i+1][j]);
			}
		}
		cout << dp[i][j] << "\n";
	}
	return 0;
}

C++: #include <iostream>
#include <vector>
#include <algorithm>
#include <numeric>
#define FOR(i,b,e) for(int i=b;i<e;i++)
#define REP(i,n) FOR(i,0,n)
using namespace std;

int dp[1001][1001];
string s1, s2;

int lcs(int n1, int n2) {
  if (dp[n1][n2] != -1) return dp[n1][n2];
  
  dp[n1][n2] = (s1[n1-1] == s2[n2-1]) ? (1 + lcs(n1 - 1, n2 - 1)) : max(lcs(n1 - 1, n2), lcs(n1, n2 - 1));
  return dp[n1][n2];
}

int main() {
	cin.tie(0);
 	ios::sync_with_stdio(false);


  int q; cin >> q;
  REP(i, q) {
    REP(i, 1001) {
      REP(j, 1001) {
        dp[i][j] = -1;
      }
    }
    REP(i, 1001) dp[i][0] = 0;
    REP(i, 1001) dp[0][i] = 0;

    cin >> s1;
    cin >> s2;

    cout << lcs(s1.length(), s2.length()) << endl;
  }
}

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

int main(){
    int N;
    cin>>N;
    int ans[151];
    if(N>20){
        for(int i=0;i<N;i++){
            string inp1,inp2;
            cin>>inp1;
            cin>>inp2;
            int dp[101][101]={};
            for(int j=1;j<=inp1.size();j++){
                for(int k=1;k<=inp2.size();k++){
                    if(inp1[j-1]==inp2[k-1]){
                        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[inp1.size()][inp2.size()];
        }
    }else{
        for(int i=0;i<N;i++){
            string inp1,inp2;
            cin>>inp1;
            cin>>inp2;
            int dp[1001][1001]={};
            for(int j=1;j<=inp1.size();j++){
                for(int k=1;k<=inp2.size();k++){
                    if(inp1[j-1]==inp2[k-1]){
                        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[inp1.size()][inp2.size()];
        }
    }
    for(int i=0;i<N;i++){
        cout<<ans[i]<<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[1001][1001];
  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=1;j<x.size()+1;j++){
      for(int k=1;k<y.size()+1;k++){
	if(x[j-1]==y[k-1]){
	  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()][y.size()]<<'\n';  
  }
  return 0;
}