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++: #define _CRT_SECURE_NO_WARNINGS
#include <cstdio>
#include <cstdlib>
#include <string>
#include <iostream>
#include <queue>

using namespace std;

const char *X, *Y;
int X_length, Y_length;

int table_lcs[1001][1001];

int lcs(int x_begin, int y_begin) {
	int i, j, to;
	int max = 0;
	int v_lcs;
	bool alreadySeenTable[256];
	if (table_lcs[x_begin][y_begin] != -1) {
		return table_lcs[x_begin][y_begin];
	}
	
	for (i = 0; i < 256; i++) {
		alreadySeenTable[i] = false;
	}
	i = x_begin;
	to = Y_length-1;
	while(i <= X_length-1) {
		j = y_begin;
		if (alreadySeenTable[X[i]] == true) {
			i++;
			continue;
		}
		bool found = false;
		while (j <= to) {
			if (X[i] == Y[j]) {
				v_lcs = lcs(i + 1, j + 1) + 1;
				if (v_lcs > max) {
					max = v_lcs;
				}
				found = true;
				break;
			}
			else {
				j++;
			}
		}
		if (found == false) {
			alreadySeenTable[X[i]] = true;
			i++;
		}
		else {
			alreadySeenTable[X[i]] = true;
			i++;
			to = j - 1;
		}
	}
	return table_lcs[x_begin][y_begin] = max;
}

int lcs2(int x_begin, int y_begin) {
	int i, j, to;
	int max = 0;
	int v_lcs;
	if (table_lcs[x_begin][y_begin] != -1) {
		return table_lcs[x_begin][y_begin];
	}

	i = x_begin;
	to = Y_length - 1;
	while (i <= X_length - 1) {
		j = y_begin;
		bool found = false;
		while (j <= to) {
			if (X[i] == Y[j]) {
				v_lcs = lcs2(i + 1, j + 1) + 1;
				if (v_lcs > max) {
					max = v_lcs;
				}
				found = true;
				break;
			}
			else {
				j++;
			}
		}
		if (found == false) {
			i++;
		}
		else {
			i++;
			to = j - 1;
		}
	}
	return table_lcs[x_begin][y_begin] = max;
}

int main() {

	int N;
	cin >> N;
	string stringX, stringY;

	for (int i = 1; i <= N; i++) {
		for (int i = 0; i < 1001; i++) {
			for (int j = 0; j < 1001; j++) {
				table_lcs[i][j] = -1;
			}
		}
		cin >> stringX >> stringY;
		X = stringX.c_str();
		X_length = stringX.size();
		Y = stringY.c_str();
		Y_length = stringY.size();
		printf("%d\n", lcs2(0, 0));
	}
	return 0;
}

C++: #include <iostream>
#include <string>
#include <cstring>
#include <cmath>
#include <algorithm>
#include <vector>
#include <fstream>
#include <numeric>


using namespace std;

#define max(a,b) a > b ? a : b
#define min(a,b) a < b ? a : b

const int INF = 1 << 29;        // 十分大きい値にする

// 入力
string S, T;

// DP テーブル
int dp[1010][1010];
int n;
int ans[150];

int main() {

    cin >> n;

    for (int i = 0; i < n; i++)
    {
        cin >> S >> T;
        memset(dp, 0, sizeof(dp));    // 初期化
        for (int i = 0; i < S.size(); ++i) {
            for (int j = 0; j < T.size(); ++j) {
                if (S[i] == T[j]) dp[i + 1][j + 1] = max(dp[i + 1][j + 1], dp[i][j] + 1);
                dp[i + 1][j + 1] = max(dp[i + 1][j + 1], dp[i + 1][j]);
                dp[i + 1][j + 1] = max(dp[i + 1][j + 1], dp[i][j + 1]);
            }
        }

        ans[i] = dp[S.size()][T.size()];

    }

    for (int i = 0; i < n; i++)
    {
        cout << ans[i] << endl;
    }

}

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

int lcs(const string& X,
    const string& Y) 
{
    int lenX = X.length();
    int lenY = Y.length();
    vector<vector<int>> dp(lenX + 1, vector<int>(lenY + 1));
    for (int i = 1; i <= lenX; ++i) {
        for (int j = 1; j <= lenY; ++j) {
            if (X[i-1] == Y[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[lenX][lenY];
}

int main() {
    int q;
    cin >> q;
    vector<string> Xs(q);
    vector<string> Ys(q);
    for (int i = 0; i < q; ++i) {
        cin >> Xs[i];
        cin >> Ys[i];
    }
    for (int i = 0; i < q; ++i) {
        cout << lcs(Xs[i], Ys[i]) << endl;
    }



}

C++: // #include <bits/stdc++.h>
#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <map>
#include <cmath>
#include <numeric>
#include <set>
#include <queue>
#include <cstdio>
using namespace std;
#define rep(i, n) for(int i=0;i<n;i++)
#define irep(i, n) for(int i=n-1;i>=0;i--)
#define lrep(i, n) for(long long i=0;i<n;i++)
typedef long long ll;
typedef vector<long long> llv;
typedef vector<vector<long long> > llvv;

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;
    rep(i,n){
        cin >> s1 >> s2;
        cout << lcs(s1, s2) << endl;
    }
    return 0;
}

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

using namespace std;

int lcslen[1001][1001]={0};
int compute_lcslen(const string &x,const string &y);

int main(){
  int q;
  cin >> q;
  for(int i=0;i<q;++i){
    string x,y;
    cin >> x;
    cin >> y;
    cout << compute_lcslen(x,y) << endl;
  }

  return 0;
}

int compute_lcslen(const string &x,const string &y){
  for(int i=1;i<=x.length();++i){
    for(int j=1;j<=y.length();++j){
      if(x[i-1]==y[j-1]){
        lcslen[i][j] = lcslen[i-1][j-1]+1;
      }else{
        lcslen[i][j] = max(lcslen[i-1][j],lcslen[i][j-1]);
      }
    }
  }
  return lcslen[x.length()][y.length()];
}