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 <vector>
using namespace std;

#define MAXX 1024

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

int LCS(char* a, char* b){
	int al = 0, bl = 0;
	for (int i = 0; i < MAXX; i++){
		if (a[i] == '\0') al = i;
		if (b[i] == '\0') bl = i;
		if (al != 0 && bl != 0) break;
	}
	vector< vector<int> > table(al, vector<int>(bl, 0));
	for (int i = 0; i < al + bl - 1; i++){
		for (int j = max(i - al + 1, 0); j <= min(bl - 1, i); j++){
			if (a[i - j] == b[j]){
				if (i - j == 0 || j == 0){
					table[i - j][j] = 1;
				}
				else{
					table[i - j][j] = table[i - j - 1][j - 1] + 1;
				}
			}
			else{
				if (i - j == 0 && j == 0){
					table[i - j][j] = 0;
				}
				else if (i - j == 0 && j != 0){
					table[i - j][j] = table[i - j][j - 1];
				}
				else if (i - j != 0 && j == 0){
					table[i - j][j] = table[i - j - 1][j];
				}
				else{
					table[i - j][j] = max(table[i - j - 1][j], table[i - j][j - 1]);
				}
			}
		}
	}
	return table[al-1][bl-1];
}

int main(){
	int n, dum;
	scanf("%d", &n);
	char a[MAXX], b[MAXX];
	for (int i = 0; i < n; i++){
		scanf("%s", &a);
		scanf("%s", &b);
		printf("%d\n", LCS(a, b));
	}

	return 0;
}

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

int lcs(string str1, string str2){
  int C[1001][1001];
  int max = 0;

  str1 = ' ' + str1;
  str2 = ' ' + str2;

  for(int i = 1 ; i <= str1.size() ; i++) C[i][0] = 0;
  for(int j = 1 ; j <= str2.size() ; j++) C[0][j] = 0;

  for(int i = 1 ; i <= str1.size() ; i++){
    for(int j = 1 ; j <= str2.size() ; j++){
      if(str1[i] == str2[j]){
	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 if(C[i][j -1] > C[i - 1][j]) C[i][j] = C[i][j - 1];
      }

      if(max > C[i][j]) max = max;
      else if(C[i][j] > max) max = C[i][j];

    }
  }

  return max;
}

int main(){
  string str1, str2;
  int n;

  cin >> n;

  for(int i = 0 ; i < n ; i++){
    cin >> str1 >> str2;
    cout << lcs(str1, str2)-1 << endl;
  }

  return 0;
}

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 x, y;

    cin >> N;

    for(i = 0 ; i < N ; i++) {
        cin >> x;
        cin >> y;
        printf("%d\n", lcs(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 c[N + 1][N + 1];
    int m = X.size();
    int n = Y.size();
    int maxl = 0;
    X = ' ' + X;    // X[0]に空白を挿入
    Y = ' ' + Y;    // Y[0]に空白を挿入
    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 (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;
}