Go: package main

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

var sc = bufio.NewScanner(os.Stdin)

func scanInt() int {
	num, _ := strconv.Atoi(scanString())
	return num
}

func scanString() string {
	sc.Scan()
	return sc.Text()
}

func init() {
	sc.Split(bufio.ScanWords)
}

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

func lcs(a, b string) int {
	lenA := len(a)
	lenB := len(b)
	dp := make([][]int, lenA+1)
	for i := range dp {
		dp[i] = make([]int, lenB+1)
	}

	for i := 1; i <= lenA; i++ {
		for j := 1; j <= lenB; j++ {
			if a[i-1] == b[j-1] {
				dp[i][j] = dp[i-1][j-1] + 1
			} else {
				dp[i][j] = max(dp[i][j-1], dp[i-1][j])
			}
		}
	}
	return dp[lenA][lenB]
}

func main() {
	n := scanInt()
	w := bufio.NewWriter(os.Stdout)
	for i := 0; i < n; i++ {
		a := scanString()
		b := scanString()
		fmt.Fprintln(w, lcs(a, b))
	}
	w.Flush()
}

C++: #include "iostream"
#include "string.h"

using namespace std;

int L[1001][1001];

int lcs( char s1[], char s2[], int l1, int l2 ) {

	if (L[l1][l2] != 0)return L[l1][l2];

	if (l1 == 0 || l2 == 0) return 0;
	else if (s1[l1-1] == s2[l2-1]) L[l1][l2] = lcs(s1, s2, l1 - 1, l2 - 1) + 1;
	else {
		int lsc1 = lcs(s1, s2, l1 - 1, l2);
		int lsc2 = lcs(s1, s2, l1, l2 - 1);

		if (lsc1 > lsc2) L[l1][l2] = lsc1;
		else L[l1][l2] = lsc2;
	}

	return L[l1][l2];
}

int main() {

	int n;
	char s1[1000], s2[1000];

	cin >> n;

	int ans[150];

	for (int i = 0; i < n; i++) {
		cin >> s1;
		cin >> s2;

		ans[i] = lcs(s1, s2, strlen(s1), strlen(s2));
	}

	for (int i = 0; i < n; i++) {
		cout << ans[i] << endl;
	}

	return 0;
}

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 ;
}