Go: package main

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

// define
var (
	sc = bufio.NewScanner(os.Stdin)
)

func bordersInt(in_map [][]int, invalid int) [][]int{
	H, W := len(in_map), len(in_map[0])
	out_map := make([][]int, H+2)
	for h:=0; h<H+2; h++ {
		out_map[h] = make([]int, W+2)
		for w:=0; w<W+2; w++ {
			out_map[h][w] = invalid
		}
	}
	for h:=0; h<H; h++{
		for w:=0; w<W; w++{
			out_map[h+1][w+1] = in_map[h][w] 
		}
	}
	return out_map
}

func bordersString(in_map [][]string, invalid string) [][]string{
	H, W := len(in_map), len(in_map[0])
	out_map := make([][]string, H+2)
	for h:=0; h<H+2; h++ {
		out_map[h] = make([]string, W+2)
		for w:=0; w<W+2; w++ {
			out_map[h][w] = invalid
		}
	}
	for h:=0; h<H; h++{
		for w:=0; w<W; w++{
			out_map[h+1][w+1] = in_map[h][w] 
		}
	}
	return out_map
}

func scanIntLine(len int) []int{
	arr := make([]int, len)
	for i:=0; i<len; i++{
		sc.Scan()
		tmp, err := strconv.Atoi(sc.Text())
		if err == nil{
			arr[i] = tmp
		}
	}
	return arr
}

func scanStringLine(len int) []string{
	arr := make([]string, len)
	for i:=0; i<len; i++{
		sc.Scan()
		arr[i] = sc.Text()
	}
	return arr
}

func scanIntSplit(len int) []int{
	arr := make([]int, len)
	sc.Scan()
	for i, v := range strings.Split(sc.Text(), " "){
		tmp, err := strconv.Atoi(v)
		if err == nil{
			arr[i] = tmp
		}
	}
	return arr
}

func maxInt(args... int) int{
	sort.Ints(args)
	return args[len(args)-1]
}

func main(){
	buf := make([]byte, 0)
    sc.Buffer(buf, 1000000009)
	var n int 
	fmt.Scan(&n)
	dp := make([][]int, 1003)
	for i:=0; i<1003; i++ {
		dp[i] = make([]int, 1003)
	}
	input_lines := scanStringLine(2*n)
	for i:=0; i<n; i++ {
		S, T := input_lines[2*i], input_lines[2*i+1]
		lenS, lenT := len(S), len(T)
		for i:=1; i<lenS+1; i++ {
			for j:=1; j<lenT+1; j++ {
				if S[i-1] == T[j-1] {
					dp[i][j] = dp[i-1][j-1]+1
				} else if S[i-1] != T[j-1] && dp[i-1][j] > dp[i][j-1] {
					dp[i][j] = dp[i-1][j]
				} else {
					dp[i][j] = dp[i][j-1]
				}
				// if S[i-1] == T[j-1] {
				// 	dp[i][j] = maxInt(dp[i-1][j-1]+1, dp[i-1][j], dp[i][j-1])
				// } else {
				// 	dp[i][j] = maxInt(dp[i-1][j], dp[i][j-1])
				// }
			}
		}
		fmt.Println(dp[lenS][lenT])
	}
}

C++: #include <bits/stdc++.h>

#define M_PI       3.14159265358979323846   // pi

using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef vector<ll> VI;
typedef pair<ll, ll> P;
typedef tuple<ll, ll, ll> t3;
typedef tuple<ll, ll, ll, ll> t4;
typedef tuple<ll, ll, ll, ll, ll> t5;

#define rep(a,n) for(ll a = 0;a < n;a++)
#define repi(a,b,n) for(ll a = b;a < n;a++)

using namespace std;

static const ll INF = 1e15;

struct LongestCommonSubsequence {
    static const int max_length = 1001;
    std::vector<std::vector<int>> dp;
    std::vector<std::vector<int>> pre;
    std::string s, t;

    LongestCommonSubsequence(std::string left, std::string right) {
        s = "+" + left;
        t = "*" + right;
        dp.assign(max_length, std::vector<int>(max_length, 0));
        pre.assign(max_length, std::vector<int>(max_length, 0));
    }

    void lcs() {

        for (int si = 1; si < s.size(); si++) {
            for (int ti = 1; ti < t.size(); ti++) {
                if (s[si] == t[ti]) {
                    dp[si][ti] = dp[si - 1][ti - 1] + 1;
                    pre[si][ti] = 1;
                }
                else if (dp[si - 1][ti] > dp[si][ti - 1]) {
                    dp[si][ti] = dp[si - 1][ti];
                    pre[si][ti] = 2;
                }
                else {
                    dp[si][ti] = dp[si][ti - 1];
                    pre[si][ti] = 3;
                }
            }
        }
    }

    std::string solve() {
        std::string ans = "";

        int si = s.size() - 1;
        int ti = t.size() - 1;
        while (si >= 1 && ti >= 1) {
            if (pre[si][ti] == 1) {
                ans += s[si];
                si--, ti--;
            }
            else if (pre[si][ti] == 2) {
                si--;
            }
            else {
                ti--;
            }
        }

        reverse(ans.begin(), ans.end());
        return ans;
    }
};

int main() {
    ll q;
    cin >> q;
    rep(i, q) {
        string s, t;
        cin >> s >> t;
        LongestCommonSubsequence seq(s, t);
        seq.lcs();
        cout << seq.solve().size() << endl;
    }
    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;

int main(){

  int n;
  int dp[1111][1111];

  cin >> n;
  while(n--){
    string str1, str2;
    cin >> str1 >> str2;

    memset(dp,0,sizeof(dp));

    for(int i = 1; i <= str1.size(); i++){
      for(int j = 1; j <= str2.size(); j++){
        if(str1[i-1] == str2[j-1]){
          dp[i][j] = dp[i-1][j-1] + 1;
        }else dp[i][j] = max(dp[i-1][j],dp[i][j-1]);
      }
    }
    cout << dp[str1.size()][str2.size()] << endl;

  }
}

C++: #include <algorithm>
#include <cassert>
#include <climits>
#include <cmath>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <string>
#include <vector>

using namespace std;
typedef long long ll;

int dp[1001][1001];

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int q;
  cin >> q;
  vector<string> xs(q), ys(q);
  for (int i = 0; i < q; i++) {
    cin >> xs[i] >> ys[i];
  }

  for (int i = 0; i < q; i++) {
    fill(dp[0], dp[1001], 0);
    string x = xs[i], y = ys[i];
    for (int j = 0; j < x.size(); j++) {
      for (int k = 0; k < y.size(); k++) {
        if (x[j] == y[k]) {
          dp[j + 1][k + 1] = dp[j][k] + 1;
        } else {
          dp[j + 1][k + 1] = max(dp[j][k + 1], dp[j + 1][k]);
        }
      }
    }

    cout << dp[x.size()][y.size()] << endl;
    ;
  }
  return 0;
}

C++: #include <algorithm>
#include <iostream>
#include <string>
#include <vector>
#include <utility>
#include <queue>
#include <cmath>
#include <set>
#include <iomanip>

using namespace std;

typedef long long ll;

int get_LCS(string x, string y){
  int nx = x.size(), ny = y.size();
  int dp[nx+1][ny+1];
  for(int i=0;i<=ny;i++) dp[0][i] = 0;
  for(int i=0;i<=nx;i++) dp[i][0] = 0;
  for(int i=1;i<=nx;i++){
    for(int j=1;j<=ny;j++){
      if(x[i] == y[j]) dp[i][j] = dp[i-1][j-1] + 1;
      else dp[i][j] = max(dp[i][j-1], dp[i-1][j]);
    }
  }
  return dp[nx][ny];
}

int main(){
  cin.tie(0);
  ios_base::sync_with_stdio(false);
  int q; cin >> q;
  for(int i=0;i<q;i++){
    string x, y; cin >> x >> y;
    cout << get_LCS(x, y) << endl;
  }
}

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

int lcs(string s1,string s2)
{
	int m = s1.size();
	int n = s2.size();
	int c[1005][1005];
	for (int i = 1; i <= m; i++)c[i][0] = 0;
	for (int j = 1; j <= n; j++)c[0][j] = 0;
	int maxz = 0;
	s1 = " " + s1;
	s2 = " " + s2;
	for(int i=1;i<=m;i++)
		for (int j = 1; j <= n; j++) {
			if (s1[i] == s2[j])
				c[i][j] = c[i-1][j-1] + 1;
			else {
				c[i][j] = max(c[i - 1][j], c[i][j - 1]);
			}
			maxz = max(maxz, c[i][j]);
		}
	return maxz;
}
int main()
{
	int N;
	scanf("%d", &N);
	while (N--) {
		string s1, s2;
		cin >> s1>>s2;
		cout << lcs(s1, s2) << endl;
	}
	return 0;
}

C++: /*
http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=ALDS1_10_C&lang=jp
*/
#include<iostream>
#include<string>
using namespace std;

//最長共通部分列
int LCS(string x , string y){
  int x_len=x.size();
  int y_len=y.size();
  int dp[x_len+1][y_len+1];
  //初期化
  for(int i=0;i<=x_len;i++){
    for(int j=0;j<=y_len;j++){
      dp[i][j]=0;
    }
  }
  for(int i=0;i<x_len;i++){
    for(int j=0;j<y_len;j++){
      if(x[i]==y[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]);
      }
    }
  }
  return dp[x_len][y_len];
}
int main(){
  int q;
  cin>>q;
  for(int i=0;i<q;i++){
    string str1,str2;
    cin>>str1>>str2;
    cout<<LCS(str1,str2)<<"\n";
  }
}