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 <stdio.h>
#include <string.h>
#define rep(i, n) for(int i = 0; i < n; ++i)
#define repi(i, n) for(int i = 1; i < n; ++i)

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

int main(void) {
  int n;
  scanf("%d", &n);
  rep(i, n) {
    char x[1500], y[1500], h, w;
    scanf("%s", x);
    scanf("%s", y);
    h = strlen(x), w = strlen(y);
    int dp[h][w], len[w], maxs = 0;
    rep(j, h) rep(k, w) dp[j][k] = 0;
    rep(j, w) if(x[0] == y[j]) dp[0][j] = 1, maxs = 1;
    len[0] = 0;
    repi(j, w) len[j] = max(dp[0][j - 1], len[j - 1]);
    repi(j, h) {
      rep(k, w) if(x[j] == y[k]) {
        dp[j][k] = len[k] + 1;
        if(maxs < dp[j][k]) maxs = dp[j][k];
      }
      repi(k, w) len[k] = max(dp[j][k - 1], max(len[k], len[k - 1]));
      /*rep(k, w) printf("%d ", len[k]);
      printf("\n");*/
    }
    /*printf("\n");
    rep(j, h) {
      rep(k, w) printf("%d ", dp[j][k]);
      printf("\n");
    }*/
    printf("%d\n", maxs);
  }
  return 0;
}

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

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

        int DP[1024][1024] = {};

        for(int i=1;i<=(int)X.size();++i){
            for(int j=1;j<=(int)Y.size();++j){
                if(X[i] == Y[j]){ // 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]);
                }
            }
        }
        cout << DP[(int)X.size()][(int)Y.size()] << endl;
    }
}

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

int main(){
    int N;
    cin >> N;
    for(int c=0; c<N; ++c){
        string X,Y;
        cin >> X >> Y;
        int xlen = (int)X.size();
        int ylen = (int)Y.size();

        vector<vector<int> > L(xlen+1 ,vector<int>(ylen+1, 0));

        for(int i=1;i<=xlen;++i){
            for(int j=1;j<=ylen;++j){
                if(X[i-1] == Y[j-1]){
                    L[i][j] = L[i-1][j-1] + 1;
                } else {
                    L[i][j] = max(L[i-1][j], L[i][j-1]);
                }
            }
        }
        cout << L[xlen][ylen] << endl;
    }
}

C++: // http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=ALDS1_10_C
#include <iostream>
#include <iomanip>
#include <algorithm>
#include <vector>

#define debug(x) cout << #x << "==" << x << endl;

using namespace std;

//??\???
#define MAX_LEN 1000
int N;
int dp[MAX_LEN + 1][MAX_LEN + 1];

void print_dp_table(int n, int m) {
  for(int i = 0; i < n; i++) {
    for(int j = 0; j < m; j++) {
      cout <<setw(2) << dp[i][j];
    }
    cout << "\n";
  }
  cout << "\n";
}

int main() {
  ios::sync_with_stdio(false);

  cin >> N;

  string s1, s2;

  while( cin >> s1 >> s2 ) {

    std::vector<char> a;
    std::vector<char> b;
    for(char& c : s1) {
      a.push_back(c);
    }
    for(char& c : s2) {
      b.push_back(c);
    }


    // dp ????????????????????????
    fill(dp[0], dp[MAX_LEN + 1], 0);

    for( int i = 0; i < (int)a.size(); i++) {
      for( int j = 0; j < (int)b.size(); j++) {
        if( a[i] == b[j] ) {
          dp[i + 1][j + 1] = dp[i][j] + 1;
        } else {
          dp[i + 1][j + 1] = max( dp[i + 1][j], dp[i][j + 1]);
        }
      }
    }

    // print_dp_table(a.size(), b.size());
    cout << dp[a.size()][b.size()] << endl;

  }

  return 0;
}

C++: #include<iostream>
#include<cstring>
using namespace std;
int main(){
  int n; cin>>n;
  for(int i=0;i<n;++i){
    char str1[1001],str2[1001]; cin>>str1>>str2;
    int len1=strlen(str1),len2=strlen(str2);
    int dp[1001][1001]={},max=0;
    for(int i=0;i<len1;++i){
      for(int j=0;j<len2;++j){
	if(str1[i]==str2[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+1][j];
	  else dp[i+1][j+1]=dp[i][j+1];
	}
	if(max<dp[i+1][j+1]) max=dp[i+1][j+1];
      }
    }
    cout<<max<<endl;
  }
  return 0;
}

C++: #include <bits/stdc++.h>
#define rep(i,j,k) for(int i=(int)j;i<(int)k;i++)
#define itrep(i,x) for(auto i=(x).begin(); i!=(x).end();i++)
#define Sort(x) sort((x).begin(),(x).end())
#define all(x) (x).begin(),(x).end()
#define fi first
#define se second
#define vi vector<int>
//#define INF 1<<31-1
#define INFL 1e18
#define MOD 1000000007
#define pb push_back
#define MP make_pair
#define PI 3.1415926535
typedef long long int ll;
//typedef std::pair<int,int> P;
int D=1;
int dx[4]={0,1,0,-1},dy[4]={-1,0,1,0};
int INF=INT_MAX;

using namespace std;

int main(){
    string s,t;
    int n;
    cin>>n;
    rep(i,0,n){
        cin>>s>>t;
        vector<vector<int>> v(s.size()+1,vector<int>(t.size()+1));
        int ans=0;
        
        rep(i,0,s.size())v[i][0]=0;
        rep(i,0,t.size())v[0][i]=0;
        
        rep(i,1,s.size()+1){
            rep(j,1,t.size()+1){
                if(s[i]==t[j]){
                    v[i][j]=v[i-1][j-1]+1;
                }else {
                    v[i][j]=max(v[i-1][j],v[i][j-1]);
                }
            ans=max(ans,v[i][j]);
            }
        }
        cout<<ans<<endl;
    }
    
    return 0;
}