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 <cstdio>
#include <cstring>
#include <vector>
#include <set>
#include <map>
#include <algorithm>

using namespace std;

const int kMax = 1000 + 10;

int n, m;
char a_str[kMax], b_str[kMax];
int dp[kMax];

vector<int> init_num() {
    vector<int> res;
    map<char, set<int> > table;
    for(int i = 0;i < n;++ i) {
        if(table.count(a_str[i]) > 0) table[a_str[i]].insert(i);
        else {
            set<int> s;
            s.insert(i);
            table[a_str[i]] = s;
        }
    }
    for(int i = 0;i < m;++ i) {
        if(table.count(b_str[i]) > 0) {
            for(auto it = table[b_str[i]].rbegin();it != table[b_str[i]].rend();++ it) {
                res.push_back(*it);
            }
        }
    }
    return res;
}

int solve() {
    n = strlen(a_str);
    m = strlen(b_str);
    vector<int> num = init_num();
    if(num.empty()) return 0;
    int res = 1;
    dp[0] = num[0];
    for(int i = 1;i < num.size();++ i) {
        if(dp[res - 1] < num[i]) dp[res ++] = num[i];
        else dp[lower_bound(dp, dp + res, num[i]) - dp] = num[i];
    }
    return res;
}

int main() {
    int q;
    scanf("%d", &q);
    while(q --) {
        scanf("%s%s", a_str, b_str);
        printf("%d\n", solve());
    }
    return 0;
}

C++: #include <bits/stdc++.h>
typedef long long ll;
using namespace std;
ll a7=1000000007;
ll inf=1000000000000000;
typedef pair<ll,ll> l_l;
#define rep(i,l,r) for(ll i=l;i<=r;i++)
#define pb push_back


ll min(ll a,ll b){
    if(a<b)return a;
    return b;
}
ll max(ll a,ll b){
    if(a>b)return a;
    return b;
}

ll Max(ll a,ll b,ll c){
    if(a<0){
        a=-inf;
    }
    if(b<0){
        b=-inf;
    }
    if(c<0){
        c=-inf;
    }
    ll ans=max(max(a,b),c);
    if(ans<0){
        return -2;
    }else{
        return ans;
    }
}

int main(){
    ll q;cin>>q;
    string x,y;
    ll ans[q];
    ll dp[2000][2000];  //xのi文字目までと、yのj文字目までの最長の長さ
    rep(ii,0,q-1){
        cin>>x>>y;
        rep(i,0,y.size()){
            dp[0][i]=0;
        }
        rep(i,0,x.size()-1){
            rep(j,0,y.size()-1){
                if(x[i]==y[j]){
                    dp[i+1][j+1]=Max(dp[i][j]+1,dp[i+1][j],dp[i][j+1]);
                }else{
                    dp[i+1][j+1]=Max(dp[i][j],dp[i+1][j],dp[i][j+1]);
                }
                //cout<<dp[i+1][j+1]<<' ';
            }
            //cout<<endl;
        }
        ans[ii]=dp[x.size()][y.size()];
    }
    rep(i,0,q-1){
        cout<<ans[i]<<endl;
    }
    return 0;
}

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

string X;
string Y;

int calc(int x, int y, vector<vector<int> >& Memo){
    if (X[x] == '\0' || Y[y] == '\0') return 0;
    if (Memo[x][y] != -1) return Memo[x][y];

    int unuse = calc(x + 1, y, Memo);
    int use = 0;
    int y_target = Y.find(X[x], y);
    if (y_target == string::npos) {
        use = 0;
    } else {
        use = calc(x + 1, y_target + 1, Memo) + 1;
    }
    return Memo[x][y] = max(unuse, use);
}

int main(){
    int q;
    cin >> q;
    for (int i = 0; i < q; i++) {
        cin >> X;
        cin >> Y;
        vector<int> tmp(Y.size(), -1);
        vector<vector<int> > Memo(X.size(), tmp);
        cout << calc(0, 0, Memo) << endl;
    }

    return 0;
}

C++: #include<cstdio>
#include<cstring>
#define N 1000

int LCS[N][N];

int LCSLength(char X[], int m, char Y[], int n){
	for(int i=0;i<=m;i++)
		LCS[i][n] = 0;
	for(int j=0;j<=n;j++)
		LCS[m][j] = 0;
	for(int i=m-1;i>=0;i--){
		for(int j=n-1;j>=0;j--){
			LCS[i][j] = LCS[i+1][j+1];
			if(X[i] == Y[j])
				LCS[i][j]++;
			if(LCS[i][j+1] > LCS[i][j])
				LCS[i][j] = LCS[i][j+1];
			if(LCS[i+1][j] > LCS[i][j])
				LCS[i][j] = LCS[i+1][j];
		}
	}
	return LCS[0][0];
}

int main(){
	char X[N],Y[N];
	int num;
	scanf("%d",&num);
	for(int i=1;i<=num;i++){
		scanf("%s %s",X,Y);
		int m = strlen(X);
		int n = strlen(Y);
		printf("%d\n",LCSLength(X,m,Y,n));
	}
	return 0;
}

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

const int N = 1000;

int lcs(string s1, string s2) {
    int c[N + 1][N + 1];
    int m = s1.size();
    int n = s2.size();
    s1 = ' ' + s1;
    s2 = ' ' + s2;
    c[0][0]  = 0;
    for (int i = 1; i <= m; i++)
        c[i][0]  = 0;
    for (int i = 1; i <= n; i++)
        c[0][i] = 0;

    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]);
            }
        }
    }
    return c[m][n];
}

int main() {
    int n;
    string s1, s2;
    cin >> n;
    for (int i = 0; i < n; i++) {
        cin >> s1 >> s2;
        cout << lcs(s1, s2) << "\n";
    }
    return 0;
}

C++: #include<iostream>
using namespace std;
#include<algorithm>
#include<string>
int n, m;
string s, t;
int dp[1001][1001];
int main()
{
    int p;
    cin >> p;
    while(p>0)
    {
        p--;
        cin >> s >> t;
        int n = s.size();
        int m = t.size();
        for (int i = 1; i <= n; i++)
            dp[i][0] = 0;
        for (int i = 0; i < m; i++)
            dp[0][i] = 0;
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < m; j++) {
                if (s[i] == t[i]) {
                    dp[i + 1][j + 1] = dp[i][j] + 1;
                }
                else {
                    dp[i + 1][j + 1] = max(dp[i][j + 1], dp[i + 1][j]);
                }
            }
        }
        cout << dp[n][m] << endl;
    }

}