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 <vector>
#include <list>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <ctime>
#include <string>
#include <climits>
#include <tuple>
using namespace std;
typedef long long ll;
typedef pair<int,int> P;
const int MAX_N=55555;
bool is_prime[MAX_N];
int prime[MAX_N];
int main(){
  int n;
  cin>>n;
  int dp[1001][1001];
  for(int nn=0;nn<n;nn++){
    string s1,s2;
    cin>>s1>>s2;
    for(int i=0;i<1001;i++)fill(dp[i],dp[i]+1001,0);
    for(int i=0;i<s1.size();i++){
      for(int j=0;j<s2.size();j++){
        if(s1[i]==s2[j]) dp[i+1][j+1]=max(dp[i][j]+1,max(dp[i][j+1],dp[i+1][j]));
        else dp[i+1][j+1]=max(dp[i+1][j],dp[i][j+1]);
      }
    }
    cout<<dp[s1.size()][s2.size()]<<endl;
  }
  return 0;
}

C++: #include<stdio.h>
#include<iostream>
#include<string>
#include<math.h>


using namespace std;int n[1003][1003]={};
int main(){

string A,B;
int N;
cin>>N;
for(int I=0;I<N;I++){
	cin>>A;cin>>B;

	
	int max=0;
	for(int i=0;i<(int)A.size();i++)
		for(int j=0;j<(int)B.size();j++)
			{
				
				if(A[i]==B[j])n[i+1][j+1]=n[i][j]+1;
				else{
					n[i+1][j+1]=n[i+1][j];
				if(n[i][j+1]>n[i+1][j])n[i+1][j+1]=n[i][j+1];
				}
				
		}
		/*
		for(int i=0;i<=(int)A.size();i++){cout<<endl;
		for(int j=0;j<=(int)B.size();j++){cout<<n[i][j];}}
		*/
		for(int i=A.size()+0;i>=0;i--){int c=0;int y=i;
		for(int j=B.size()+0;j>=0;j--)
		{if(n[y][j]==n[y-1][j-1]+1&&y>0){y--;c++;
		}
	}
		if(max<c)max=c;
		}
		cout<<max<<endl;
}
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 = 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<algorithm>
#include<cstdlib>
#include<cmath>
#include<vector>
#include<list>

using namespace std;

int n;
string x,y;

vector<vector<int> > q(1001,vector<int>(1001,-1));

int search(int i,int j){
  int ans;
  if(i<0 || j<0) return 0;
  if(q[i][j] != -1) return q[i][j];
  if( x[i] == y[j] ){
    ans=max( {search(i-1,j-1)+1,search(i-1,j),search(i,j-1)} );
    q[i][j]=ans;
    return ans;
  }
  else{
    ans=max( search(i-1,j),search(i,j-1) );
    q[i][j]=ans;
    return ans;
  }

}


int main(void){

  cin>>n;

  for(int i=0;i<n;i++){
    cin>>x;
    cin>>y;

    for(int ix=0;ix<1001;ix++){
      for(int iy=0;iy<1001;iy++){
        q[ix][iy]=-1;
      }
    }

    search( x.size(),y.size() );
    cout << q[x.size()-1][y.size()-1] << endl;
  }



  return 0;
}

C++: #include<iostream>
#include<string>
#include<algorithm>
#include<vector>
#include<limits.h>
using namespace std;
static const int n=1000;
static const int m=1000;

int lcs(string X,string Y){
	int i,j,c[m+1][n+1];
	int m=X.size();
	int n=Y.size();
    
	for (i=0;i<m+1;i++) c[i][0]=i;
	for (j=0;j<n+1;j++) c[0][j]=j;
	for (i=1;i<m+1;i++){
		for (j=1;j<n+1;j++){
			int min=c[i-1][j]+1;
			if (min>c[i][j-1]+1)
				min=c[i][j-1]+1;
            if ((X[i-1]==Y[j-1])&&(min>c[i-1][j-1]+1))
				min=c[i-1][j-1]+1;
			c[i][j]=min;
		}
	}
	return m+n-c[m][n];
}

int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);
	
	string s1,s2;
	int m,i;	cin >> m;
	
	for (i=0;i<m;i++){
	cin >> s1 >> s2;
	cout << lcs(s1,s2) << 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=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;
}

C++: #include <bits/stdc++.h>
using namespace std;

int main() {
  int q; cin >> q;
  string A, B; cin >> A >> B;
  for (int i=0; i<q; i++) {
    vector<vector<int>> LCS(A.length()+1, vector<int>(B.length()+1,0));
    for (int j=1; j<=A.length(); j++) {
      for (int k=1; k<=B.length(); k++) {
        if(A[j]==B[k]) LCS[j][k]=LCS[j-1][k-1]+1;
        else LCS[j][k]=max(LCS[j-1][k],LCS[j][k-1]);
      }
    }
    cout << LCS[A.length()][B.length()] << "\n";
  }
}

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

#define N 1000

int lcs(string X,string Y){
	int c[N+1][N+1];
	int m = X.size();
	int n = Y.size();
	X = ' ' + X;
	Y = ' ' + Y;
	for(int i=0;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(X[i]==Y[j]){
				c[i][j] = c[i-1][j-1]+1;
			}else if(c[i][j-1]>=c[i-1][j]){
				c[i][j] = c[i][j-1];
			}else{
				c[i][j] = c[i-1][j];
			}
		}
	}
	return c[m][n];
}

int main(){
	int n;
	string X,Y;
	cin >> n;
	for(int i=0;i<n;i++){
		cin >> X >> Y;
		printf("%d\n",lcs(X,Y));
	}
	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=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;
}