Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

var sc = bufio.NewScanner(os.Stdin)

func scanInt() int {
	num, _ := strconv.Atoi(scanString())
	return num
}

func scanString() string {
	sc.Scan()
	return sc.Text()
}

func init() {
	sc.Split(bufio.ScanWords)
}

func max(a, b int) int {
	if a > b {
		return a
	}
	return b
}

func lcs(a, b string) int {
	lenA := len(a)
	lenB := len(b)
	dp := make([][]int, lenA+1)
	for i := range dp {
		dp[i] = make([]int, lenB+1)
	}

	for i := 1; i <= lenA; i++ {
		for j := 1; j <= lenB; j++ {
			if a[i-1] == b[j-1] {
				dp[i][j] = dp[i-1][j-1] + 1
			} else {
				dp[i][j] = max(dp[i][j-1], dp[i-1][j])
			}
		}
	}
	return dp[lenA][lenB]
}

func main() {
	n := scanInt()
	w := bufio.NewWriter(os.Stdout)
	for i := 0; i < n; i++ {
		a := scanString()
		b := scanString()
		fmt.Fprintln(w, lcs(a, b))
	}
	w.Flush()
}

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

int main() {
    int dataSet;
    std::cin >> dataSet;

    for(int count = 0; count < dataSet; count++) {
        std::string x, y;
        std::cin >> x;
        std::cin >> y;

        std::vector< std::vector<int> > dp;
        dp.resize(x.length());
        for(auto itr = dp.begin(); itr < dp.end(); itr++) {
            itr->resize(y.length());
        }

        for(int xIndex = 0; xIndex < x.length(); xIndex++) {
            for(int yIndex = 0; yIndex < y.length(); yIndex++) {
                int top, topleft, left;
                top = 0; topleft = 0; left = 0;
                if(xIndex != 0) {
                    top = dp[xIndex - 1][yIndex];
                }
                if(yIndex != 0){
                    left = dp[xIndex][yIndex - 1];
                }
                if(xIndex != 0 && yIndex != 0) {
                    topleft = dp[xIndex - 1][yIndex - 1];
                }

                if(x[xIndex] == y[yIndex]) {
                    dp[xIndex][yIndex] = topleft + 1;
                } else {
                    dp[xIndex][yIndex] = top < left ? left : top;
                }
            }
        }

        std::cout << dp.back().back() << std::endl;
    }

    return 0;
}

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

using std::cin;
using std::cout;
using std::cerr;
using std::endl;

// 最長共通部分列 ... len(s) == m, len(t) == n とすると, O(mn)
int lcs(std::string s, std::string t) {
  std::vector<std::vector<int> > dp(s.size() + 1, std::vector<int>(t.size() + 1, 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 if (dp[i - 1][j] >= dp[j][i - 1]) {
        dp[i][j] = dp[i - 1][j];
      }
      else {
        dp[i][j] = dp[i][j - 1];
      }
    }
  }

  return dp[s.size()][t.size()];
}

int main() {
  int q;
  std::string s, t;
  cin >> q;
  while (cin >> s >> t) {
    cout << lcs(s, t) << 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 = 1; i <= m; i++) c[i][0] = 0;
  for ( int j = 1; i <= 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 <iostream>
#include <algorithm>
#include<string>
using namespace std;

static const int N = 1000;
int dp[N + 1][N + 1];

int lcs(string x, string y)
{
    int m = x.length();
    int n = y.length();
    x = ' ' + x;
    y = ' ' + y;

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

    int res = 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
                dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]);
        }
    }

    return dp[m][n];
}

int main()
{
    int n;
    cin >> n;
    string x1, x2;
    for (int i = 0; i < n; i++)
    {
        cin >> x1 >> x2;
        cout << lcs(x1, x2) << endl;
    }
    return 0;
}

C++: #include <bits/stdc++.h>
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define REP(i,n) for(int i=0;i < (n);i++)
#define ALL(obj) (obj).begin(),(obj).end()
#define SCANF(i) int i;scanf("%d",&i)
typedef long long ll;
using namespace std;
using P = pair<int,int>;
const long long INF = 1LL << 60;
const int IINF=100000000;
const int MOD = (int)1e9 + 7;
//約数列挙
vector<long long> divisor(long long n) {
    vector<long long> ret;
    for (long long i = 1; i * i <= n; i++) {
        if (n % i == 0) {
            ret.push_back(i);
            if (i * i != n) ret.push_back(n / i);
        }
    }
    //sort(ret.begin(), ret.end()); // 昇順に並べる
    return ret;
}
vector<int> dx={1,0,-1,0};vector<int> dy={0,-1,0,1};

signed main () {
    int n;cin >> n;
    REP(i,n){
        string s,t;cin >> s >> t;
        int slen=s.length();int tlen=t.length();
        vector<vector<int>> lcm(slen+1,vector<int>(tlen+1,0));
        REP(i,s.length())REP(j,t.length()){
            if(s[i]==t[j]){
                lcm[i+1][j+1]=max({lcm[i][j+1],lcm[i+1][j],lcm[i][j]+1});
            }
            lcm[i+1][j+1]=max({lcm[i+1][j+1],lcm[i+1][j],lcm[i][j+1]});
        }
        cout << lcm[slen][tlen] << endl;
    }

}

C++: #include <iostream>
#include <string>
#include <stack>
#include <queue>
#include <vector>
#include <list>
#include <set>
#include <map>
#include <algorithm>

#include <cstdio>

using namespace std;
#define rep(i, n) for (int i = 0; i < (n); i++)
#define rep1(i, s, n) for (int i = (s); i <= (n); i++)
#define rrep(i, n) for (int i = (n) - 1; i >= 0; i--)
#define rrep1(i, s, n) for (int i = (s); i >= (n); i--)
#define print_array(ary, size) cout << ary[0]; rep1(i, 1, size - 1) cout << ' ' << ary[i]; cout << endl;
typedef long long ll;
typedef unsigned long long ull;


int dp[1000][1000];

int getLCS(string* s1, string* s2, int s1i, int s2i)
{
	int ret;
	int cand1, cand2;

	if (s1i < 0 || s2i < 0) {
		return 0;
	}
	else if (dp[s1i][s2i] != -1) ret = dp[s1i][s2i];
	else if ((*s1)[s1i] == (*s2)[s2i]) {
		ret = getLCS(s1, s2, s1i - 1, s2i - 1) + 1;
	}
	else {
		cand1 = getLCS(s1, s2, s1i, s2i - 1);
		cand2 = getLCS(s1, s2, s1i - 1, s2i);
		ret = max(cand1, cand2);
	}
	dp[s1i][s2i] = ret;

	return ret;
}

int main()
{
	int q;
	int ans;
	string s1, s2;

	cin >> q;
	rep(i, q) {
		rep(j, 1000) {
			rep(k, 1000) dp[j][k] = -1;
		}
		cin >> s1 >> s2;
		ans = getLCS(&s1, &s2, s1.length() - 1, s2.length() - 1);
		cout << ans << endl;
	}

	return 0;
}