Go: package main

import (
	"fmt"
)

func main() {
	var q int
	fmt.Scan(&q)

	for i := 0; i < q; i++ {
		var x, y string
		fmt.Scan(&x)
		fmt.Scan(&y)

		xs := []rune(x)
		ys := []rune(y)

		xn := len(xs)
		yn := len(ys)
		dp := make([][]int, xn+1)
		for j := 0; j <= xn; j++ {
			dp[j] = make([]int, yn+1)
		}

		for j := 1; j <= xn; j++ {
			for k := 1; k <= yn; k++ {
				dp[j][k] = max(dp[j-1][k], dp[j][k-1])
				if xs[j-1] == ys[k-1] {
					dp[j][k] = max(dp[j][k], dp[j-1][k-1] + 1)
				} else {
					dp[j][k] = max(dp[j][k], dp[j-1][k-1])
				}
			}
		}
		fmt.Println(dp[xn][yn])
	}
}

func max(a, b int) int {
	if a < b {
		return b
	} else {
		return a
	}
}

C++: #include<cstdio>
#include<queue>
#include<utility>
#include<cstring>
#include<stack>
#include<algorithm>
#include<cmath>
#include<iostream>
#define MAX_N 100001
#define INF 2147483647
#define REP(i,n) for(int i=0;i<(int)(n);i++)
void init(int n);
int find(int n);
void unite(int x,int y);
bool same(int x, int y);
int dx[4] = {1,0,0,-1};
int dy[4] = {0,1,-1,0};
using namespace std;

struct edge{
  int from,to,cost;
};
typedef vector<vector<edge> > AdjList;
AdjList graph;
typedef pair<int , int> P;
bool comp(const edge& e1, const edge& e2){
  return e1.cost < e2.cost;
}
int E,V;
edge es[100001];
int kruskal(){
  sort(es,es+E,comp);
  init(V);
  int res = 0;
  for(int i=0;i<E;i++){
    edge e = es[i];
    if(!same(e.to,e.from)){
      unite(e.to,e.from);
      res += e.cost;
    }
  }
  return res;
}


int main()
{
  int co=0,dp[1001][1001];
  dp[0][0] = 0;
  dp[0][1] = 0;
  dp[1][0] = 0;
  string x,y;
  cin >> co;
  REP(i,co){
    cin >> x;
    cin >> y;
    REP(i,x.length())REP(j,y.length()){
      if(i == 0 || j== 0){
        if(x[i] == y[j])
          dp[i][j] = 1;
        else
          dp[i][j] = 0;
      }
      else{if(x[i] == y[j]){
        dp[i][j] = dp[i-1][j-1]+1;
        }else{
        dp[i][j] = max(dp[i-1][j],dp[i][j-1]);
        }
      }
    }
    cout << dp[x.length()-1][y.length()-1] << endl;
  }
  
  return 0;
}

int par[MAX_N];
int ranks[MAX_N];

//n要素で初期化
void init(int n){
  REP(i,n){
    par[i] = i;
    ranks[i] = 0;
  }

}

//木の根を求める
int find(int x){
  if(par[x] == x){
    return x;
  }else{
    return par[x] = find(par[x]);
  }
}

void unite(int x,int y){
  x = find(x);
  y = find(y);
  if(x == y) return ;
  if(ranks[x] < ranks[y]){
    par[x] = y;
  }else{
    par[y] = x;
    if(ranks[x] == ranks[y]) ranks[x]++;
  }
}

bool same(int x, int y){
  return find(x) == find(y);
}

C++: #include <iostream>
#include <string>
#include <vector>
#include <set>
#include <cmath>
#include <algorithm>
#include <iomanip>
#include <map>
#include <queue>
using ll = long long;
using namespace std;

const ll MOD = 1e9 + 7;

int main(void)
{
    int N;
    cin >> N;

    while (N--)
    {
        string s, t;
        cin >> s >> t;

        int dp[1010][1010];
        for (int i = 0; i < 1010; ++i)
            for (int j = 0; j < 1010; ++j)
                dp[i][j] = 0;

        int n = s.size(), m = t.size();

        for (int i = 0; i < n; ++i)
        {
            for (int j = 0; j < m; ++j)
            {
                if (s[i] == t[j])
                {
                    dp[i + 1][j + 1] = max(dp[i + 1][j + 1], dp[i][j] + 1);
                }
                else
                {

                    dp[i + 1][j + 1] = max({dp[i + 1][j + 1], dp[i][j], dp[i + 1][j], dp[i][j + 1]});
                }
            }
        }

        cout << dp[n][m] << 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 <iostream>
#include <algorithm>
#include <cstdio>
#include <cmath>
#include <string>
#include <cctype>
#include <stack>
#include <queue>
#include <vector>
#include <cstdlib>
#include <list>
#define _USE_MATH_DEFINES
#include <math.h>

using namespace std;

int lcs(string X, string Y) {
	int n, m;
	int c[1001][1001] = { 0 };
	int maxlcs = 0;;

	n = X.size();
	m = Y.size();


	X = ' ' + X;
	Y = ' ' + Y;
	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 (X[i] == Y[i])
				c[i][j] = c[i - 1][j - 1] + 1; 
			else
				c[i][j] = max(c[i][j - 1],c[i-1][j]);

			maxlcs = max(maxlcs, c[i][j]);
		}
	}
	return maxlcs;
}

int main() {

	int n;
	string S1, S2;

	cin >> n;
	for (int i = 0; i < n; i++) {
		cin >> S1;
		cin >> S2;
		cout << lcs(S1, S2) << endl;
	}

	return 0;
}

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

int main(){
    int n;cin>>n;
    for(int i=0;i<n;i++){
        string X,Y;cin>>X>>Y;
        int M[X.size()][Y.size()]={};
        //まずは端を埋める
        int flg=0;
        for(int i=0;i<Y.size();i++){//Xの一文字目を固定
            if(X[0]==Y[i])flg=1;
            if(flg)M[0][i]=1;
        }
        flg=0;
        for(int i=0;i<X.size();i++){//Yの一文字目を固定
            if(Y[0]==X[i])flg=1;
            if(flg)M[i][0]=1;
        }
        for(int i=1;i<X.size();i++){
            for(int j=1;j<Y.size();j++){
                if(X[i]==Y[j]){
                    M[i][j]=M[i-1][j-1]+1;
                }else{
                    M[i][j]=max(M[i-1][j],M[i][j-1]);
                }
            }
        }

        cout<<M[X.size()-1][Y.size()-1]<<endl;
    }
    return 0;
}

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

static const int N = 1000;

int longestCommonSubsequence(string X, string Y)  {
  int c[N + 1][N + 1];
  int m = X.size();
  int n = Y.size();
  int max1 = 0;
  X = ' ' + X;
  Y = ' ' + Y;
  for (int i = 0; i <= m; i++) 
    c[i][0] = 0;
  for (int j = 1; j <= n; j++)
    s[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]);
      }
      max1 = max(max1, c[i][j]);
    }
  }
  return max1;
}
 
int main()  {
  string s1, s2;
  int n;
  cin >> n;
  for (int i = 0; i < n; i++)  {
    cin >> s1 >> s2;
  cout << longestCommonSubsequence(s1, s2) << endl;
  }
  return ;
}

C++: #include <bits/stdc++.h>
 
#define ALL(l)  (l).begin(),(l).end()
#define rep(i,n) for(ll (i)=0;(i)<(n);(i)++)
#define rep2(i, s, n) for (int i = (s); i < (int)(n); i++)
using namespace std;
typedef long long ll;
//const ll mod =  1000000007;
const ll maxn = 1000000000;

//---------------------------------------------------------------------------------------------------
using vi = vector<int>; // intの1次元の型に vi という別名をつける
using vll = vector<ll>; // intの1次元の型に vi という別名をつける
using vvll = vector<vll>; // intの2次元の型に vvi という別名をつける
using vs = vector<string>; // stringの1次元の型に vs という別名をつける
using pll = pair<ll, ll>; // これ以降 pii という型名はpair<ll, ll> と同じ意味で使える
//---------------------------------------------------------------------------------------------------

int main(){
  int n;
  cin>>n;
  rep(i,n){
      string s,t;
      cin>>s>>t;
      
      vvll dp(s.size()+1,vll(t.size()+1));
      rep(j,s.size()+1)dp.at(j).at(0)=0;
      rep(j,t.size()+1)dp.at(0).at(j)=0;
      
      rep(j,s.size()){
          rep(k,t.size()){
              if(s.at(j)==t.at(k))dp.at(j+1).at(k+1)=dp.at(j).at(k)+1;
              else dp.at(j+1).at(k+1)=max(dp.at(j+1).at(k),dp.at(j).at(k+1));
          }
      }
      cout<<dp.at(s.size()).at(t.size())<<endl;
  }
}