Go: package main

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

// I/O
type Scanner struct {
	sc *bufio.Scanner
}

func NewScanner() *Scanner {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	sc.Buffer(make([]byte, 1024), int(1e+9))
	return &Scanner{sc}
}

func (s *Scanner) nextStr() string {
	s.sc.Scan()
	return s.sc.Text()
}

func (s *Scanner) nextInt() int {
	i, e := strconv.Atoi(s.nextStr())
	if e != nil {
		panic(e)
	}
	return i
}

func (s *Scanner) nextFloat() float64 {
	f, e := strconv.ParseFloat(s.nextStr(), 64)
	if e != nil {
		panic(e)
	}
	return f
}

func (s *Scanner) nextRuneSlice() []rune {
	return []rune(s.nextStr())
}

func (s *Scanner) nextIntSlice(n int) []int {
	res := make([]int, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextInt()
	}
	return res
}

func (s *Scanner) nextFloatSlice(n int) []float64 {
	res := make([]float64, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextFloat()
	}
	return res
}

// Arithmetic
func max(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m < i {
			m = i
		}
	}
	return m
}

func min(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m > i {
			m = i
		}
	}
	return m
}

func abs(x int) int {
	if x > 0 {
		return x
	}
	return -x
}

func pow(x, y int) int {
	res := 1
	for i := 0; i < y; i++ {
		res *= x
	}
	return res
}

func ceil(a, b int) int {
	if a%b == 0 {
		return a / b
	} else {
		return a/b + 1
	}
}

// Sort
type RuneSlice []rune

func (a RuneSlice) Len() int           { return len(a) }
func (a RuneSlice) Less(i, j int) bool { return a[i] < a[j] }
func (a RuneSlice) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }

// Main
func main() {
	sc := NewScanner()
	wtr := bufio.NewWriter(os.Stdout)
	Q := sc.nextInt()
	for q := 0; q < Q; q++ {
		X, Y := sc.nextStr(), sc.nextStr()
		xLen, yLen := len(X), len(Y)
		dp := make([][]int, xLen+1)
		for i := 0; i <= xLen; i++ {
			dp[i] = make([]int, yLen+1)
		}
		for x := 0; x <= xLen; x++ {
			for y := 0; y <= yLen; y++ {
				if x == 0 || y == 0 {
					dp[x][y] = 0
				} else if X[x-1] == Y[y-1] {
					dp[x][y] = dp[x-1][y-1] + 1
				} else {
					dp[x][y] = max(dp[x-1][y], dp[x][y-1])
				}
			}
		}
		fmt.Fprintln(wtr, dp[xLen][yLen])
	}

	wtr.Flush()
}

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

int main(){
  vector <vector<int> > dp;
  string x,y;
  int n;

  cin >> n;
  for(int times=0;times<n;times++){
    int ans =0;

    cin >> x >> y;
    dp.resize(y.size()+1);
    for(int i=0;i<=y.size();i++){
      dp[i].resize(x.size()+1);
    }

    for(int i=0;i<=y.size();i++){
      dp[i][0]=0;
    }
    for(int i=0;i<=x.size();i++){
      dp[0][i]=0;
    }

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

    cout << ans << endl;
  }
}

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

#define MAX 100

using namespace std;

int lcs(string s1, string s2) {
    int C[MAX+1][MAX+1];
    int m = s1.size();
    int n = s2.size();
    for (int i = 0; i <= m; ++i) {
        C[i][0] = 0;
    }
    for (int j = 0; j <= n; ++j) {
        C[0][j] = 0;
    }

    for (int i = 1; i <= m; ++i) {
        for (int j = 1; j <= n; ++j) {
            if (s1[i-1] == s2[j-1]) {
                C[i][j] = C[i-1][j-1] + 1;
            }
            else {
                C[i][j] = max(C[i][j-1], C[i-1][j]);
            }
        }
    }

    return C[m][n];
}

int main() {
    int n;
    scanf("%d", &n);
    for (int i = 0; i < n; ++i) {
        string s1, s2;
        cin >> s1 >> s2;
        cout << lcs(s1, s2) << endl;
    }
    return 0;
}

C++: #include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
const int maxx = 1010;
int c[maxx][maxx];

int lcs(char s1[],char s2[]) {
	int m = strlen(s1), n = strlen(s2);
	for (int i = 1; i <= m; i++)
		c[i][0] = 0;
	for (int i = 1; i <= n; i++)
		c[0][i] = 0;

	int ans = 0;
	for (int i = 1; i <= m; i++) {
		for (int j = 1; j <= n; j++) {
			if (s1[i] == s2[j])
				c[i][j] = c[i - 1][j - 1] + 1;
			else
				c[i][j] = max(c[i - 1][j], c[i][j - 1]);
			ans = max(ans, c[i][j]);
		}
	}
	return ans;
}
int main()
{
	char s1[maxx], s2[maxx];
	int t;
	scanf("%d", &t);
	for (int i = 0; i < t; i++) {
		scanf("%s %s", s1, s2);
		printf("%d\n", lcs(s1, s2));
	}

	return 0;
}

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

static const int ra =1000;

int lcs(string A, string B){
  int ca[ra+1][ra+1];
  int mi =A.size();
  int ni = B.size();
  int most = 0;

  A = ' ' + A;
  B = ' '+B;

  for(int i=1;i<=mi;i++){
    ca[i][0]=0;
  }
  for(int j=0;j<=ni;j++){
    ca[0][j] = 0;
  }

  for(int i =1;i<=mi;i++){
    for(int j=1;j<=ni;j++){
      if(A[i] == B[j]){
	ca[i][j] = ca[i-1][j-1]+1;
      }
      else{
	ca[i][j] = max(ca[i-1][j],ca[i][j-1]);
      }
      most = max(most,ca[i][j]);
    }
  }
  return most;
}

int main(){
  string K1,K2;
  int num,i;
  cin >>num ;
  for(i=0;i<num;i++){
    cin >> K1 >> K2;
    cout << lcs(K1,K2) << endl;
  }
  return 0;
}

C++: #include<iostream>
#include<algorithm>
#include<vector>
#include<string>
#define NIL -1
using namespace std;

int count(const string& X, int i, const string Y, int j,
          vector<vector<int> >& MEMO){
    if (i >= X.size() || j >= Y.size()) return 0;
    if (MEMO[i][j] != NIL) return MEMO[i][j];
    int next_X = count(X, i + 1, Y, j, MEMO);
    int j_next = Y.find(X[i], j);
    if (j_next == string::npos) return MEMO[i][j] = next_X;
    int saiyou = count(X, i + 1, Y, j_next + 1, MEMO) + 1;
    return MEMO[i][j] = max(saiyou, next_X);
}

int main(){
    int q;
    cin >> q;
    for (int i = 0; i < q; i++) {
        string X, Y;
        cin >> X >> Y;
        vector<vector<int> > MEMO(X.size(), vector<int>(Y.size(), NIL));
        cout << count(X, 0, Y, 0, MEMO) << endl;
    }
    return 0;
}

C++: #include <bits/stdc++.h>
#define _GLIBCXX_DEBUG
#define rep(i,n) for (ll i = 0; i < (n); ++i)
using namespace std;
using ll = long long;
using P = pair<ll,ll>;

int main()
{
    int q;
    cin>>q;
    vector<int>ansvec(q);
    int count=0;
    while (count<q)
    {string x,y;
     cin >> x>>y;
     vector<vector<int>>dp(x.size()+1,vector<int>(y.size()+1));
     rep(i,x.size())
     {
         rep(j,y.size())
         {
             dp[i+1][j+1]= (x[i]==y[j]) ? dp[i][j]+1 : max(dp[i+1][j],dp[i][j+1]) ;
         }
     }
     ansvec[count]=dp[x.size()][y.size()];
     count++;
    }
    
    rep(i,q)
    {
        cout<<ansvec[i]<<endl;
    }
   
    return 0;
}

C++: #include <stdio.h>
#include <string.h>
#define rep(i, n) for(int i = 0; i < n; ++i)
#define repi(i, n) for(int i = 1; i < n; ++i)

int max(int a, int b) {
  return a > b ? a : b;
}

int main(void) {
  int n;
  scanf("%d", &n);
  rep(i, n) {
    char x[1500], y[1500], h, w;
    scanf("%s", x);
    scanf("%s", y);
    h = strlen(x), w = strlen(y);
    int dp[h][w], len[w];
    rep(j, h) rep(k, w) dp[j][k] = 0;
    rep(j, w) if(x[0] == y[j]) dp[0][j] = 1;
    len[0] = 0;
    repi(j, w) len[j] = max(dp[0][j - 1], len[j - 1]);
    repi(j, h) {
      rep(k, w) if(x[j] == y[k]) dp[j][k] = len[k] + 1;
      repi(k, w) len[k] = max(dp[j][k - 1], max(len[k], len[k - 1]));
      /*rep(k, w) printf("%d ", len[k]);
      printf("\n");*/
    }
    /*printf("\n");
    rep(j, h) {
      rep(k, w) printf("%d ", dp[j][k]);
      printf("\n");
    }*/
    int maxs = 0;
    rep(j, w) if(maxs < dp[h - 1][j]) maxs = dp[h - 1][j];
    printf("%d\n", maxs);
  }
  return 0;
}