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<cstdio>
#include<string>
using namespace std;

#define MAX_N 1000
#define MAX_M 1000

void solve();

string s, t;
int dp[MAX_N + 1][MAX_M + 1];

void solve(){
	for(int i = 0; i < s.size(); i++){
		for(int j = 0; j < t.size(); j++){
			if(s[i] == t[j]){
				dp[i + 1][j + 1];
					dp[i + 1][j + 1] = dp[i][j] + 1;
				} else {
					dp[i + 1][j + 1] = max(dp[i][j], dp[i + 1][j]);
				}
			}
		}
		cout << dp[s.size()][t.size()] << endl;
}

int main(){
	int n;
	cin >> n;
	for(int i = 0; i < n; i++){
		cin >> s >> t;
		solve();
	}
	return 0;
}

C++: #include <iostream>
#include <algorithm>
#include <string>
using namespace std;
const int MAX=1001;
int lcs(string X,string Y) 
{
    int i=0,j=0,c[MAX][MAX],x=X.length(),y=Y.length();
    for(i=0;i<=x;i++)c[i][0]=0;
    for(i=0;i<=y;i++)c[0][i]=0;
    for(i=1;i<=x;i++) 
    for(j=1;j<=y;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];
    return c[x][y];
}
int main()
{
    int n;cin>>n;
    string X,Y;
    while(n--)
    {
        cin>>X>>Y;
        cout<<lcs(X,Y)<<endl;
    }
}

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

#define MAX 1000

int lcs(string X, string Y) {
    int c[MAX+1][MAX+1];
    int m = X.size();
    int n = Y.size();
    int i, j;
    int maxlen = 0;
    X = " " + X;
    Y = " " + Y;

    for (i = 1 ; i <= m ; i++ ) c[i][0] = 0;
    for (j = 1 ; j <= n ; j++ ) c[0][j] = 0;

    for(i = 1 ; i <= m ; i++ ) {
        for(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]);
            }
            maxlen = max(maxlen, c[i][j]);
        }
    }
    return maxlen;
}

int main (void) {
    int N, i;
    string a, b;

    cin >> N;

    for(i = 0 ; i < N ; i++) {
        cin >> a;
        cin >> b;
        cout << lcs(a, b) << endl;
    }

    return 0;
}

C++: /*
** Longest Common Subsequence
*/

# include <cstdio>
# include <cstring>
# include <algorithm>
using namespace std;

const int MAX = 1000 + 5;

char s1[MAX], s2[MAX];
int c[MAX][MAX];

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

    for (int i = 0; i < m; i++) {
        for (int j = 0; j < n; j++) {
            if (s1[i] == s2[j]) {
                c[i][j] = c[i - 1][j - 1] + 1;
            }
            else {
                c[i][j] = max(c[i][j - 1], c[i - 1][j]);
            }
            maxl = max(maxl, c[i][j]);
        }
    }

    return maxl;
}

void solve() {
    int n;
    scanf("%d", &n);
    while (n--) {
        scanf("%s %s", s1, s2);
        printf("%d\n", lcs());
    }
}

int main() {
    // freopen("infile", "r", stdin);
    // freopen("outfile", "w", stdout);
    solve();
    return 0;
}

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

int main(void){
    int Q;
    cin >> Q;
    
    for(int q = 0;q < Q;q++){
        string x,y;
        cin >> x >> y;
        
        int dp[x.size()+1][y.size()+1];
        for(int i = 0;i < x.size()+1;i++){
            for(int j = 0;j < y.size()+1;j++){
                dp[i][j] = 0;
            }
        }
        
        for(int i = 0;i < x.size();i++){
            for(int j = 0;j < y.size();j++){
                if(x[i] == y[j]){
                    dp[i+1][j+1] = max(dp[i+1][j+1],dp[i][j]+1);
                }
                dp[i+1][j+1] = max(dp[i+1][j+1],dp[i][j+1]);
                dp[i+1][j+1] = max(dp[i+1][j+1],dp[i+1][j]);
            }
        }
        cout << dp[x.size()][y.size()] << endl;
    }
}

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

#define N 1000

int lcs(string x, string y) {
  int i, j, m, n, lcs[N+1][N+1];
  
  m = x.length();
  n = y.length();
  // indexずれを補正
  x = ' ' + x;
  y = ' ' + y;
  
  // 初期値
  for (i = 0; i < m + 1; i++) lcs[i][0] = 0;
  for (j = 0; j < n + 1; j++) lcs[0][j] = 0;
  // 漸化式
  for (i = 1; i <= m; i++) {
    for (j = 1; j <= n; j++) {
      if (x[i] == y[j]) lcs[i][j] = lcs[i-1][j-1] + 1;
      else lcs[i][j] = max(lcs[i-1][j], lcs[i][j-1]);
    }
  }

  return lcs[m][n];
}

int main() {
  int i, q, lcs_arr[N];
  string x, y;

  cin >> q;

  for (i = 0; i < q; i++) {
    cin >> x;
    cin >> y;
    lcs_arr[i] = lcs(x, y);
  }    

  for (i = 0; i < q; i++) cout << lcs_arr[i] << endl;
    
  return 0;
}

C++: #include <iostream>
#include <algorithm>
#include <cstdlib>
#include <cstring>
#include <fstream>

#define SMAX 1000
#define QMAX 150

using namespace std;

int main()
{
  int q;
  cin >> q;
  
  char X[SMAX], Y[SMAX];
  int LCS[SMAX+1][SMAX+1] = {0};
  int Anwser[QMAX];
  for(int i = 0; i<q; i++) {
    scanf("%s",X);
    scanf("%s",Y);
    int size_X = strlen(X);
    int size_Y = strlen(Y);
    for(int j = 0; j <= size_X; j++) LCS[j][0] = 0;
    for(int j = 0; j <= size_Y; j++) LCS[0][j] = 0;

    for(int j = 1; j <= size_X; j++) {
      for(int k = 1; k <= size_Y; k++) {
	if(X[j-1] == Y[k-1]) LCS[j][k] = LCS[j-1][k-1] + 1;
	else LCS[j][k] = max(LCS[j-1][k], LCS[j][k-1]);
      }
    }
    Anwser[i] = LCS[size_X][size_Y];
  }

  for(int i = 0; i<q; i++) cout << Anwser[i] << endl;

  return 0;
}