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 <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;
}

C++: #include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <set>
#include <queue>
#include <map>
#include <memory.h>
using namespace std;

typedef long long ll;
typedef long double ld;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<ld> vld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

#define INF ((int)1e9)
#define INFLL ((ll)1e18)
#define MOD (1000000007LL)


int main(int argc, const char * argv[]) {
    int Q;
    string X, Y;
    cin >> Q;
    for (int q = 0; q < Q; ++q) {
        cin >> X >> Y;
        int DP[1001][1001];
        memset(DP, 0, sizeof(DP));
        for (int sx = 1; sx <= X.size(); ++sx) {
            for (int sy = 1; sy <= Y.size(); ++sy) {
                DP[sx][sy] = max(DP[sx][sy-1], DP[sx][sy-1]);
                if (X[sx] == Y[sy]) {
                    DP[sx][sy] = max(DP[sx][sy], DP[sx-1][sy-1]+1);
                }
            }
        }
        cout << DP[X.size()][Y.size()] << endl;
    }
    return 0;
}