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 <bits/stdc++.h>
using namespace std;

int main(){
  int n; cin >> n;
  for( int i = 0; i < n; i++ ){
    int dp[1010][1010];
    for( int i = 0; i < 1010; i++ ) dp[i][0] = dp[0][i] = 0;
    
    char x[1010], y[1010];
    cin >> x >> y;

    for( int i = 0; i < strlen( x ); i++ ){
      for( int j = 0; j < strlen( y ); j++ ){
	if( x[i] == y[j] ){
	  dp[i + 1][j + 1] = dp[i][j] + 1; 
	}else if( dp[i][j + 1] >= dp[i + 1][j] ){
	  dp[i + 1][j + 1] = dp[i][j + 1];
	}else{
	  dp[i + 1][j + 1] = dp[i + 1][j];
	}
      }
    }

    cout << dp[strlen( x )][strlen( y )] << endl;
  }
}

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

int lcs(string &X, string &Y) {
  int dp[1000 + 1][1000 + 1];
  int max = 0;
  int m = X.size();
  int n = Y.size();
  X = ' ' + X;
  Y = ' ' + Y;

  for (int i = 1; i <= m; i++)
    dp[i][0] = 0;

  for (int i = 1; i <= n; i++)
    dp[0][i] = 0;

  for (int i = 1; i <= m; i++) {
    for (int j = 1; j <= n; j++) {
      if (X[i] == Y[j])
	dp[i][j] = dp[i-1][j - 1] + 1;
      else if (dp[i - 1][j] >= dp[i][j - 1])
	dp[i][j] = dp[i - 1][j];
      else
	dp[i][j] = dp[i][j - 1];

      if(max < dp[i][j])
	max = dp[i][j];
    }
  }

  return max;
}

int main() {
  int N = 0;
  cin >> N;

  string X, Y;
  for (int i = 0; i < N; i++) {
    cin >> X >> Y;

    cout << lcs(X, Y) << endl;
  }

  return 0;
}

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

int c[1010][1010];

void lcs(char X[], char Y[]){
	int m = strlen(X);
	int n = strlen(Y);
	int i, j;
	for(i = 1;i <= m;i++)
		c[i][0] = 0;
	for(j = 1;j <= m;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 - 1][j], c[i][j - 1]);
		}
	}
}

int main(void){
	int q, i;
	char A[1000], B[1000];
	scanf("%d", &q);
	for(i = 0;i < q;i++){
		scanf("%s", A);
		scanf("%s", B);
		lcs(A, B);
		printf("%d\n", c[strlen(A)][strlen(B)]);
	}
	return 0;
}

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

int main(){
  int q;
  cin >> q;
  for(int m=0; m<q; m++){
    string wordx, wordy;
    cin >> wordx >> wordy;
    int L[1000][1000]={0};
    
    for(int j=0; j<wordy.size(); j++){
      for(int i=0; i<wordx.size(); i++){
	if(wordx[i]==wordy[j]){
	  L[i][j] = 1+L[i-1][j-1];
	}
	else{
	  L[i][j] = max(L[i][j-1], L[i-1][j]);
	}
      }
    }
    cout << L[wordx.size()-1][wordy.size()-1] << endl;
    
    
  }
}

C++: #include <algorithm>
#include <bitset>
#include <cctype>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <deque>
#include <functional>
#include <iomanip>
#include <iostream>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <utility>
#include <vector>
using namespace std;

int solve() {
    string x, y;
    cin >> x >> y;
    vector<vector<int>> dp(x.size() + 1, vector<int>(y.size() + 1, 0));

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

    return dp[x.size()][y.size()];
}

int main() {
    int n;
    cin >> n;
    for (int i = 0; i < n; i++) {
        cout << solve() << endl;
    }
}

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

int c[1010][1010];

void lcs(char X[], char Y[]){
	int m = strlen(X);
	int n = strlen(Y);
	int i, j;
	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 - 1] == Y[j - 1])
				c[i][j] = c[i - 1][j - 1] + 1;
			else
				c[i][j] = max(c[i - 1][j], c[i][j - 1]);
		}
	}
}

int main(void){
	int q, i;
	char A[1000], B[1000];
	scanf("%d", &q);
	for(i = 0;i < q;i++){
		scanf("%s", A);
		scanf("%s", B);
		lcs(A, B);
		printf("%d\n", c[strlen(A)][strlen(B)]);
	}
	return 0;
}

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

#define REP(i, n) for(int (i) = 0; (i) < (n); (i)++)

string str1, str2;
int dp[1001][1001];

void solve()
{
  REP(i, str1.size())
    if(str1[i] == str2[str2.size() - 1])
      dp[i][str2.size() - 1] = 1;
    else
      dp[i][str2.size() - 1] = 0;
  for(int i = str2.size() - 2; i >= 0; i--)
    if(str1[str1.size() - 1] == str2[i])
      dp[str1.size() - 1][i] = 1;
    else
      dp[str1.size() - 1][i] = dp[str1.size() - 1][i + 1];
  for(int i = str1.size() - 2; i >= 0; i--){
    for(int j = str2.size() - 2; j >= 0; j--){
      if(str1[i] == str2[j])
	dp[i][j] = dp[i + 1][j + 1] + 1;
      else
	dp[i][j] = max(dp[i + 1][j], dp[i][j + 1]);
    }
  }
}
  
int main()
{
  int q;
  cin >> q;
  cin.ignore();
  REP(i, q){
    getline(cin, str1);
    getline(cin, str2);
    fill(&dp[0][0], &dp[1001][0], -1);
    swap(str1, str2);
    solve();
    cout << dp[0][0] << endl;
  }
}