Go: package main

import (
	. "fmt"
    "math"
)

// func init() { Println("----------------------------------------") }

func main() {
    const L_MAX = 1003

	var q int
	Scanf("%d", &q)
	X := make([]string, 0, 150)
	Y := make([]string, 0, 150)
	for i := 0; i < 2 * q; i++ {
	    var tmp string
	    Scanf("%s", &tmp)

	    if i % 2 == 0 {
	        X = append(X, tmp)
	    } else {
	        Y = append(Y, tmp)
	    }
	}

    for i := 0; i < q; i++ {
        dp := make([][]int, L_MAX)
        for k, _ := range dp {
            dp[k] = make([]int, L_MAX)
        }

        x, y := X[i], Y[i]

        // init
        isXFound := false
        for c := 0; c < len(x); c++ {
            if isXFound || y[0] == x[c] {
                dp[0][c] = 1
                isXFound = true
            }
        }
        isYFound := false
        for r := 0; r < len(y); r++ {
            if isYFound || x[0] == y[r] {
                dp[r][0] = 1
                isYFound = true
            }
        }

        for r := 1; r < len(y); r++ {
            for c := 1; c < len(x); c++ {
                // dp[r][c]
                if x[c] == y[r] {
                    dp[r][c] = int(math.Max(float64(dp[r - 1][c - 1] + 1), float64(dp[r][c])))
                }

                dp[r][c] = int(math.Max(float64(dp[r][c]), math.Max(float64(dp[r - 1][c]), float64(dp[r][c - 1]))))
            }
        }
        Println(dp[len(y) - 1][len(x) - 1])

        // LCSも求めておく
        // ans := ""
        // r, c := len(y) - 1, len(x) - 1
        // for r >= 0 && c >= 0 {
        //     if y[r] == x[c] {
        //         ans = string(x[c]) + ans
        //         r--
        //         c--
        //     } else {
        //         if dp[r - 1][c] > dp[r][c - 1] {
        //             r--
        //         } else {
        //             c--
        //         }
        //     }
        // }
        // Println(ans)
    }
}

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 = 1; i <= m ; ++i) {
        C[i][0] = 0;
    }
    for (int j = 1; 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 <stdio.h>
#include <stdint.h>
#include <iostream>
#include <fstream>
#include <cassert>
#include <climits>
#include <vector>
#include <memory>
using namespace std;

#define DEBUG (0)

#if DEBUG
#define DPRINTF(...) do { \
    printf("D(L%d) %s: ", __LINE__, __func__); \
    printf(__VA_ARGS__); \
  } while (false)
#else
#define DPRINTF(...)
#endif // DEBUG


class LongestCommonSubsequence {
public:
  LongestCommonSubsequence(string s0, string s1) :
    s0_(s0),
    s1_(s1)
    {
      size_ = s0_.length() * s1_.length();
      pLongest_ = new int [size_];
      for (int i = 0; i < size_; i++)
        pLongest_[i] = kInvalid;
    }

  ~LongestCommonSubsequence()
  {
    if (pLongest_)
      free(pLongest_);
  }

  int getLCSlen();
  void printLength();

  const int kInvalid = -1;

private:
  string s0_;
  string s1_;
  int *pLongest_;
  int size_;

  int getIndex(int x, int y);
  int getLCSlenOf(int n0, int n1);
};

/*********************************
Input:
  x[0], x[1], x[2], ..., x[n-1]
  y[0], y[1], y[2], ..., y[m-1]

Algorithm:
  if x[n-1] == y[m-1]
    LCS(n-1, m-1) = LCS(n-2,m-2) + 1

  if x[n-1] != y[m-1]
    LCS(n-1, m-1) = max(LCS(n-2, m-1), LCS(n-1, m-2))

  LCS(0, *) = LCS(*, 0) = 0;

  a b c b d a b
  b d c a b a
*********************************/

int LongestCommonSubsequence::getLCSlen()
{
  int n0 = s0_.length();
  int n1 = s1_.length();
  return getLCSlenOf(n0, n1);
}


int LongestCommonSubsequence::getLCSlenOf(int n0, int n1)
{
  DPRINTF("n0 %d  n1 %d\n", n0, n1);

  assert(0 <= n0 && n0 <= s0_.length());
  assert(0 <= n1 && n1 <= s1_.length());

  if (n0 == 0 || n1 == 0)
    return 0;

  const int idx = getIndex(n0 - 1, n1 - 1);

  if (pLongest_[idx] != kInvalid)
    return pLongest_[idx];

  if (s0_[n0] == s1_[n1])
    pLongest_[idx] = getLCSlenOf(n0 - 1, n1 - 1) + 1;
  else
    pLongest_[idx] = max(getLCSlenOf(n0 - 1, n1), getLCSlenOf(n0, n1 - 1));

  return pLongest_[idx];
}


int LongestCommonSubsequence::getIndex(int x, int y)
{
  return y * s0_.length() + x;
}


void LongestCommonSubsequence::printLength()
{
  for (int i = 0; i < s0_.length(); i++)
    for (int j = 0; j < s1_.length(); j++)
      DPRINTF("pLongest_[%d][%d] %d\n", i, j, pLongest_[getIndex(i, j)]);
}


int main()
{
  int numOfPair;
  cin >> numOfPair; cin.ignore();

  DPRINTF("num of pair %d\n", numOfPair);

  for (int i = 0; i < numOfPair; i++)
  {
    string str0, str1;
    cin >> str0 >> str1; cin.ignore();

    DPRINTF("str0 %s  str1 %s\n", str0.c_str(), str1.c_str());

    LongestCommonSubsequence lcs(str0, str1);
    cout << lcs.getLCSlen() << endl;

#if (1) && DEBUG
    lcs.printLength();
#endif
  }

  return 0;
}

C++: #include <iostream>
#include <string>
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=1; i<=m; i++) {
    c[i][0]=0;
  }
  for (int j=1; 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() {
  std::ios::sync_with_stdio(false);
  cout.tie(0);
  cin.tie(0);
  int n;
  cin>>n;
  string s1,s2;
  for (int i=0; i<n; i++) {
    cin>>s1>>s2;
    cout<<lcs(s1,s2)<<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 = 1; 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++: #if 0
?????????X[0]???????????????????????\???????????¨??§???X[1],Y[1]???????????????????????????????????????
#endif

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

int main(){
	int q;
	cin >> q;
	for(int a=0;a<q;++a){
		string X,Y;
		int L[1000+10][1000+10];
		cin >> X >> Y;
		for(int i=0;i<1000;++i) //???????????\????????????L????????????
			for(int j=0;j<1000;++j)
				L[i][j]=0;
	
		for(int j=1;j<X.size()+1;++j)
			for(int k=1;k<Y.size()+1;++k){
				if(X[j-1]==Y[k-1])
					L[j][k]=1+L[j-1][k-1];
				else
					L[j][k]=max(L[j-1][k],L[j][k-1]);
			}
		cout << L[X.size()][Y.size()] << endl;
	}
}