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 <algorithm>
#include <cstring>
using namespace std;

const int Max = 1005;
int c[Max][Max];

void lcs(string s1, string s2)
{
    //memset(c, 0, sizeof(c));
    for(int i=0; i<=s1.size(); i++)
    {
        c[i][0] = 0;
    }
    for(int i=0; i<=s2.size(); i++)
    {
        c[0][i] = 0;
    }
    s1 = " " + s1;
    s2 = " " + s2;
    for(int i=1; i<=s1.size(); i++)
    {
        for(int j=1; j<=s2.size(); j++)
        {
            if(s1[i]==s2[j]) c[i][j] = c[i-1][j-1]+1;
            else
            {
                c[i][j] = max(c[i][j-1], c[i-1][j]);
            }
        }
    }
}
int main()
{
    int n;
    cin >> n;
    string s1, s2;
    for(int i=0; i<n; i++)
    {
        cin >> s1 >> s2;
        lcs(s1, s2);
        cout << c[s1.size()][s2.size()] << endl;
    }
    return 0;
}

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

string S,T;
int x[10000],y[10000];
int dp[10000][10000];
char U[53]="abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
int MAXN;

int main(){
	int q;
	cin>>q;
	for(int i=0;i<q;i++){
		MAXN=0;
		cin>>S>>T;
		for(int i=0;i<S.size();i++){
			for(int j=0;j<52;j++){
				if(S[i]==U[j]){
					x[i+1]=j;
				}
			}
		}
		for(int i=0;i<T.size();i++){
			for(int j=0;j<52;j++){
				if(T[i]==U[j]){
					y[i+1]=j;
				}
			}
		}
		for(int i=0;i<=T.size();i++){
			for(int j=0;j<=S.size();j++){
				if(i==0 || j==0){
					dp[i][j]=0;
				}
				else if(x[j]==y[i]){
					dp[i][j]=dp[i-1][j-1]+1;
				}
				else{
					dp[i][j]=max(dp[i][j-1],dp[i-1][j]);
				}
			}
		}
		for(int i=0;i<=T.size();i++){
			for(int j=0;j<=S.size();j++){
				MAXN=max(MAXN,dp[i][j]);
			}
		}
		cout<<MAXN<<endl;
	}
	return 0;
}

C++: #include <cstdio>
#include <iostream>
#include <algorithm>
#include <cstring>
using namespace std;
int main(){
  char str1[1000],str2[1000];
  int LCS[1000][1000]={0};
  int length1,length2;
  int n;
  scanf("%d",&n);
  for(int s=1;s<=n;s++){
   while(cin>>str1>>str2){
     length1=strlen(str1);
     length2=strlen(str2);
     for(int i=0;i<=length1-1;i++){
       LCS[i][0]=0;
     }
     for(int j=0;j<=length2-1;j++){
       LCS[0][j]=0;
     }
     for(int i=1;i<=length1;i++){
       for(int j=1;j<=length2;j++){
         if(str1[i-1]==str2[j-1]) {
           LCS[i][j]=LCS[i-1][j-1]+1;
         }
         else LCS[i][j]=max(LCS[i-1][j],LCS[i][j-1]);
       }
     }
     printf("%d\n",LCS[length1][length2]);
   }
 }
   return 0;
}

C++: #include<bits/stdc++.h>
#define rep(i, n) for(int i = 0; i < n; i++)

using namespace std;
typedef long long ll;
using Graph =vector<int>;
typedef pair<int,int> P;
int ans;
void lcs(){
  string X,Y; cin>>X>>Y;
  int N=X.size();
  int W=Y.size();
  int dp[1100][1100];
  rep(i,N){
    rep(j,W){
      if (X[i]==Y[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]);
      }
    }
  }
  cout<<dp[N][W]<<endl;
}
int main(){
  int K;cin>>K;
  rep(i,K) lcs();
}

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

static const int N = 1000;

int lcs(string X, string Y){
	int dp[N + 1][N + 1];
	int h = X.size();
	int w = Y.size();
	
	for(int i=0; i<h; i++){
		for(int j=0; j<w; j++){
			if(X[i]==Y[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[h][w];
}



int main(void){

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

C++: #define _USE_MATH_DEFINES
#include <iostream>
#include <fstream>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cstring>
#include <cassert>
#include <string>
#include <vector>
#include <utility>
#include <complex>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <deque>
#include <tuple>
#include <bitset>
#include <limits>
#include <algorithm>
#include <array>
#include <random>
#include <complex>
#include <regex>
#include <iomanip>
using namespace std;
typedef long double ld;
typedef long long ll;
typedef vector<int> vint;
typedef vector<ll> vll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define fcout cout << fixed << setprecision(10)
#define rep(i,n)    for(int i=0; i<(int)n; i++)
#define mp(a,b) make_pair(a,b)
#define pb push_back
#define all(x) x.begin(), x.end()
const ll inf = 1e18;
const ll mod = 1e9 + 7;

int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};

int dp[1010][1010] = {0};

int lcs(string x, string y){
    int n = x.size();
    int m = y.size();
    int ans = 0;
    for(int i=1; i<n+1; i++){
        for(int j=1; j<m+1; j++){
            if(y[j-1] == x[i-1]) dp[i][j] = dp[i-1][j-1] + 1;
            else dp[i][j] = max(dp[i][j-1], dp[i-1][j]);
            ans = max(ans, dp[i][j]);
        }
    }
    return ans;

}

int main(){
    int q;
    cin >> q;
    rep(i, q){
        string x,y;
        cin >> x >> y;
        cout << lcs(x,y) << endl;
    }
}

C++: #include<iostream>
#include<cstring>
#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(),n = y.size();
    int maxl = 0;
    x = " " + x;
    y = " " + y;
    for(int i = 0;i <= m;i++){
        c[0][i] = 0;
    }
    for(int j = 1;j <= n;j++){
        c[j][0] = 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 null = -1;
int n;
int ans;
string x,y;
int dp[1001][1001];

int dfs(int i, int j){
    if(dp[i][j] != null){
        return dp[i][j];
    }
    int res;
    if(i == 0 || j == 0){
        return 0;
    }
    
    if(x[i-1] == y[j-1]){
        res = max(dfs(i,j-1),max(dfs(i-1,j-1)+1,dfs(i-1,j)));
    }
    else{
        res = max(dfs(i,j-1),dfs(i-1,j));
    }
    dp[i][j] = res;
    return res;
}

int main(){
    for(int i=0;i<1001;i++){
        for(int j=0;j<1001;j++){
            dp[i][j] = null;
        }
    }

    cin >> n;
    for(int i=0;i<n;i++){
        cin >> x;
        cin >> y;
        int lenx = (int)x.length();
        int leny = (int)y.length();
        //cout << lenx << " " << leny << endl;
        ans = dfs(lenx,leny);
        cout << ans << endl;
        for(int j=0;j<1001;j++){
            for(int k=0;k<1001;k++){
                dp[j][k] = null;
            }
        }
    }
    return 0;

}