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>
#define rep(i, n) for (int i = 0; i < n; i++)
#define rrep(i, n) for (int i = n - 1; i >= 0; i--)
using namespace std;
using Graph = vector<vector<int>>;
#define MOD 1000000007
#define MOD2 998244353
#define INF ((1<<30)-1)
#define LINF (1LL<<60)
#define EPS (1e-10)
typedef long long ll;
typedef pair<ll, ll> P;

int main(){
    int q;
    cin >> q;
    vector<int> ans;

    rep(p, q){
        string s, t;
        cin >> s >> t;
        int n = s.size(), m = t.size();
        ll dp[1010][1010];
        memset(dp, 0, sizeof(dp));
        rep(i, n){
            rep(j, m){
                if (s[i] == t[j]) dp[i + 1][j + 1] = dp[i][j] + 1;
                else dp[i + 1][j + 1] = max(dp[i][j + 1], dp[i + 1][j]);
            }
        }
        ans.push_back(dp[n][m]);
    }

    rep(p, q) cout << ans[p] << endl;
    return 0;
}

C++: #include <iostream>
using namespace std;
int q,a,b,dp[1001][1001],ok;
string s,t;
int main(void){
    cin>>q;
    while(q--){
        cin>>s>>t;
        a=s.size();
        b=t.size();
        for(int i=1;i<=a;i++){
            for(int j=1;j<=b;j++){
                //if(i==3)cout<<s[i-1]<<" "<<t[j-1]<<endl;
                dp[i][j]=max(dp[i-1][j],dp[i][j-1]);
                if(s[i-1]==t[j-1])dp[i][j]=max(dp[i-1][j-1]+1,dp[i][j]);
            }
        }
        cout<<dp[a][b]<<endl;
        for(int j=0;j<=a;j++){
            for(int k=0;k<=b;k++){
                //cout<<dp[j][k]<<" ";
                dp[j][k]=0;
            }
            //cout<<endl;
        }
    }
}

C++: #include<iostream>
#include<string>

using namespace std;

#if 0
http://judge.u-aizu.ac.jp/onlinejudge/review.jsp?rid=2065462#1
#endif

int n;
string a, b;
string x[10000], y[10000];




int main(){
  cin >> n;
  while(n != 0){
    n = n -1;
    int longest[1000][1000];
    cin >> a;
    cin >> b;
    a = ' ' + a;
    b = ' ' + b;
    int mm = 0;
    /*
    for(int i = 0; i < a.size(); ++i){
      for(int j = 0; j < b.size(); ++j){
        
        x[i] = a;
        y[j] = b;
      }
    }
    */
   //longest[0][0] =0;
   for(int i = 1; i <= a.size(); ++i){
     longest[i][0] = 0;
    }
   for(int j = 1; j <= b.size(); ++j){
     longest[0][j] = 0;
   }
    for(int i = 1; i <= a.size(); ++i){
      for(int j = 1; j <= b.size(); ++j){
        
        /*
        if(i <= 0 || j <=0){
          longest[i][j] = 0;
        }
        */
        if(x[i] == y[j]){
          longest[i][j] = 1 + longest[i-1][j - 1];
        }
        else{
          longest[i][j] = max(longest[i][j-1], longest[i-1][j]);
        }
        mm = max(mm, longest[i-1][j-1]);
      }
    }
    //cout << a[1] << endl;
    cout << mm << endl;
  }
}

C++: #include <iostream>
#include <string>

/*int LCS(std::string str1, std::string str2, int i, int j){
  if(str1[i] == str2[j]){
    return 1;
  }
  else{
    return 0;
  }
 }
*/

int max(int a, int b, int c){
  int m = a;
  if(b > m){
    m = b;
  }
  if(c > m){
    m = c;
  }
  return m;
}

int main(){
  int q;
  std::cin >> q;
  //int ans[q];
  std::string str1, str2;
  for(int z=0; z<q; z++){
    std::cin >> str1 >> str2;
    int l1 = str1.size();
    int l2 = str2.size();
    int DP[l1+1][l2+1];

    for(int i=0; i<=l1; i++){
      DP[i][0] = 0;
    }
    for(int j=0; j<=l2; j++){
      DP[0][j] = 0;
    }

    for(int i=1; i<=l1; i++){
      for(int j=1; j<=l2; j++){
	if(str1[i-1] == str2[j-1]){
	  DP[i][j] = max(DP[i-1][j], DP[i][j-1], DP[i-1][j-1] + 1);
	}
	else{
	  DP[i][j] = max(DP[i-1][j], DP[i][j-1], DP[i-1][j-1]);
      }
    }
    //ans[z] = DP[l1][l2];
    std::cout << DP[l1][l2] << std::endl;
  }

  /*for(int z=0; z<q; z++){
    std::cout << ans[z] << std::endl;
    }*/
  return 0;
}

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

int dp[1100][1100];

int solve(string s, string t) {
  for (int i = 0; i < 1100; i++) {
    for (int j = 0; j < 1100; j++) {
      dp[i][j] = 0;
    }
  }
  for (int i = 1; i <= s.size(); i++) {
    for (int j = 1; j <= t.size(); j++) {
      if (s[i - 1] == t[j - 1]) {
        dp[i][j] = dp[i - 1][j - 1] + 1;
      }
      else {
        dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]);
      }
    }
  }
  return dp[s.size()][t.size()];
}

int main() {
  int q;
  cin >> q;
  vector<int> ans;
  for (int i = 0; i < q; i++) {
    string X, Y;
    cin >> X;
    cin >> Y;
    ans.push_back(solve(X, Y));
  }
  for (int i = 0; i < ans.size(); i++) {
    cout << ans[i] << 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 = 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;
}

C++: #include <string>
#include <iostream>
#include <algorithm>
using namespace std;
int q, n, m, dp[1007][1007]; string s, t;
int main() {
	cin >> q;
	while(q--) {
		cin >> s >> t;
		n = s.size(), m = t.size();
		for(int i = 0; i <= n; i++) dp[i][0] = 0;
		for(int j = 0; j <= n; j++) dp[0][j] = 0;
		for(int i = 1; i <= n; i++) {
			for(int j = 1; j <= n; j++) {
				dp[i][j] = (s[i - 1] == t[i - 1] ? dp[i - 1][j - 1] + 1 : max(dp[i - 1][j], dp[i][j - 1]));
			}
		}
		cout << dp[n][m] << endl;
	}
}