Go: package main

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

// define
var (
	sc = bufio.NewScanner(os.Stdin)
)

func bordersInt(in_map [][]int, invalid int) [][]int{
	H, W := len(in_map), len(in_map[0])
	out_map := make([][]int, H+2)
	for h:=0; h<H+2; h++ {
		out_map[h] = make([]int, W+2)
		for w:=0; w<W+2; w++ {
			out_map[h][w] = invalid
		}
	}
	for h:=0; h<H; h++{
		for w:=0; w<W; w++{
			out_map[h+1][w+1] = in_map[h][w] 
		}
	}
	return out_map
}

func bordersString(in_map [][]string, invalid string) [][]string{
	H, W := len(in_map), len(in_map[0])
	out_map := make([][]string, H+2)
	for h:=0; h<H+2; h++ {
		out_map[h] = make([]string, W+2)
		for w:=0; w<W+2; w++ {
			out_map[h][w] = invalid
		}
	}
	for h:=0; h<H; h++{
		for w:=0; w<W; w++{
			out_map[h+1][w+1] = in_map[h][w] 
		}
	}
	return out_map
}

func scanIntLine(len int) []int{
	arr := make([]int, len)
	for i:=0; i<len; i++{
		sc.Scan()
		tmp, err := strconv.Atoi(sc.Text())
		if err == nil{
			arr[i] = tmp
		}
	}
	return arr
}

func scanStringLine(len int) []string{
	arr := make([]string, len)
	for i:=0; i<len; i++{
		sc.Scan()
		arr[i] = sc.Text()
	}
	return arr
}

func scanIntSplit(len int) []int{
	arr := make([]int, len)
	sc.Scan()
	for i, v := range strings.Split(sc.Text(), " "){
		tmp, err := strconv.Atoi(v)
		if err == nil{
			arr[i] = tmp
		}
	}
	return arr
}

func maxInt(args... int) int{
	sort.Ints(args)
	return args[len(args)-1]
}

func main(){
	buf := make([]byte, 0)
    sc.Buffer(buf, 1000000009)
	var n int 
	fmt.Scan(&n)
	dp := make([][]int, 1003)
	for i:=0; i<1003; i++ {
		dp[i] = make([]int, 1003)
	}
	input_lines := scanStringLine(2*n)
	for i:=0; i<n; i++ {
		S, T := input_lines[2*i], input_lines[2*i+1]
		lenS, lenT := len(S), len(T)
		for i:=1; i<lenS+1; i++ {
			for j:=1; j<lenT+1; j++ {
				if S[i-1] == T[j-1] {
					dp[i][j] = dp[i-1][j-1]+1
				} else if S[i-1] != T[j-1] && dp[i-1][j] > dp[i][j-1] {
					dp[i][j] = dp[i-1][j]
				} else {
					dp[i][j] = dp[i][j-1]
				}
				// if S[i-1] == T[j-1] {
				// 	dp[i][j] = maxInt(dp[i-1][j-1]+1, dp[i-1][j], dp[i][j-1])
				// } else {
				// 	dp[i][j] = maxInt(dp[i-1][j], dp[i][j-1])
				// }
			}
		}
		fmt.Println(dp[lenS][lenT])
	}
}

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=1;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;
		int ans=lcs(s1,s2);
		if(ans<=20)cout<<ans<<endl;
		else cout<<"20"<<endl;
	}
	return 0;
}

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

using namespace std;

short dp[1010][1010];

int main(void)
{
    int q;
    cin >> q;
    while (q)
    {
        string X, Y;
        cin >> X >> Y;
        int Xs = X.size(), Ys = Y.size();
        for (int i = 0; i < Xs; i++) dp[i][0] = 0;
        for (int j = 0; j < Ys; j++) dp[0][j] = 0;
        for (int i = 0; i < Xs; i++)
        {
            for (int j = 0; j < Ys; j++)
                dp[i + 1][j + 1] = ((X[i] == Y[j]) ? dp[i][j] + 1 : max(dp[i + 1][j], dp[i][j + 1]));
        }
        cout << dp[Xs][Ys] << endl;
        q--;
    }
    return 0;
}

C++: #include <iostream>
#include <algorithm>
#include <string>
#include <cstring>
using namespace std;
int lcs(string x,string y){
	int c[x.size()+1][y.size()+1];	memset(c,0,sizeof(c));
	int m=x.size(),n=y.size();
	int mxvl=0;
	x+=" ";	y+=" ";
	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][j-1],c[i-1][j]);
			mxvl=max(mxvl,c[i][j]);
		}
	}
	return mxvl;
}

int main(){
	string x,y;
	int n;	cin>>n;
	for(int i=0;i<n;i++){
		cin>>x>>y;
		cout<<lcs(x,y)<<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=1;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<stdio.h>

int hantei(char x[], char y[]) {
  int xn = 0, yn = 0, flag = 0, i, j, max = 0;
  int c[101][101];
  
  while (flag == 0)
  {
    if (x[xn] == '\0')
    {
      xn++;
    }
    else
    {
      flag = 1;
    }
  }
  
  flag = 0;
  
  while (flag == 0)
  {
    if (y[yn] == '\0')
    {
      yn++;
    }
    else
    {
      flag = 1;
    }
  }
  for (i = 1; i < xn + 1; i++) c[i][0] = 0;
  for (j = 1; j < yn + 1; j++) c[0][j] = 0;
  
  for (i = 1; i < xn + 1; i++)
  {
    for (j = 1; j < yn + 1; j++)
    {
      if (x[i - 1] == y[j - 1])
      {
        c[i][j] = c[i - 1][j - 1] + 1;
      }
      else if (c[i - 1][j] >= c[i][j - 1])
      {
        c[i][j] = c[i - 1][j];
      }
      else
      {
        c[i][j] = c[i][j - 1];
      }
      if (max < c[i][j]) max = c[i][j];
    }
  }
  
  return max;
}

int main(void) {
  char x[1000], y[1000];
  int q, i;
  
  scanf("%d", &q);
  
  for (i = 0; i < q; i++)
  {
    scanf("%s", x);
    scanf("%s", y);
    printf("%d\n", hantei(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 m = x.size();
    int n = y.size();
    int maxl = 0;
    int c[N + 1][N + 1] ;
    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 () {
    int n ;
    cin >> n;
    string str1, str2;
    for (int i = 0; i < n; i++) {
        cin>>str1>>str2;
    
        cout << lcs(str1, str2) <<endl;
    }
    
    
    
    return 0;
}

C++: #include <iostream>
#include <cstring>
#include <algorithm>
#include <iomanip>
#include <vector>
#include <map>
#include <cmath>
#include <queue>
#include <utility>
#include <functional>
#include <deque>
#include <cctype>
#include <stack>
#include <bitset>

using ll = long long;
typedef unsigned long long ull;
typedef std::pair<ll, ll>P;

ll gcd(ll a, ll b) {
	if (b == 0) return a;
	return gcd(b, a%b);
}
ll lcm(ll a, ll b) {
	ll g = gcd(a, b);
	return a / g * b;
}

const ll mod = 1000000007;
const ll INF = 1 << 30;
const ll INF2 = 9000000000000000000LL;
bool fl = true;
int dx[4] = { 1,0,-1,0 }, dy[4] = { 0,1,0,-1 };
std::string abc = "abcdefghijklmnopqrstuvwxyz";
struct edge { ll to, cost; };
struct edge1 { ll from, to, cost; };
double pai = 3.141592653589793;

int main() {
	int q;
	std::cin >> q;
	for (int i = 0;i < q;i++) {
		std::string s, t;
		std::cin >> s >> t;
		int dp[1010][1010];
		for (int j = 0;j < s.size();j++) {
			for (int k = 0;k < t.size();k++) {
				if (s[j] == t[k])dp[j + 1][k + 1] = dp[j][k] + 1;
				else dp[j + 1][k + 1] = std::max(dp[j][k + 1], dp[j + 1][k]);
			}
		}
		std::cout << dp[s.size()][t.size()] << std::endl;
	}
}