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 _USE_MATH_DEFINES
#include <iostream>
#include <fstream>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cstring>
#include <cassert>
#include <string>
#include <vector>
#include <utility>
#include <complex>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <deque>
#include <tuple>
#include <bitset>
#include <limits>
#include <algorithm>
#include <array>
#include <random>
#include <complex>
#include <regex>
#include <iomanip>
using namespace std;
typedef long double ld;
typedef long long ll;
typedef vector<int> vint;
typedef vector<ll> vll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define fcout cout << fixed << setprecision(10)
#define rep(i,n)    for(int i=0; i<(int)n; i++)
#define mp(a,b) make_pair(a,b)
#define pb push_back
#define all(x) x.begin(), x.end()
const ll inf = 1e18;
const ll mod = 1e9 + 7;

int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};

int dp[1010][1010] = {0};

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

}

int main(){
    int q;
    cin >> q;
    rep(i, q){
        string x,y;
        cin >> x >> y;
        cout << lcs(x,y) << endl;
    }
}

C++: #include<iostream>
#include<cstring>
#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(),n = y.size();
    int maxl = 0;
    x = " " + x;
    y = " " + y;
    for(int i = 0;i <= m;i++){
        c[0][i] = 0;
    }
    for(int j = 1;j <= n;j++){
        c[j][0] = 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<string>
using namespace std;

int null = -1;
int n;
int ans;
string x,y;
int dp[1001][1001];

int dfs(int i, int j){
    if(dp[i][j] != null){
        return dp[i][j];
    }
    int res;
    if(i == 0 || j == 0){
        return 0;
    }
    
    if(x[i-1] == y[j-1]){
        res = max(dfs(i,j-1),max(dfs(i-1,j-1)+1,dfs(i-1,j)));
    }
    else{
        res = max(dfs(i,j-1),dfs(i-1,j));
    }
    dp[i][j] = res;
    return res;
}

int main(){
    for(int i=0;i<1001;i++){
        for(int j=0;j<1001;j++){
            dp[i][j] = null;
        }
    }

    cin >> n;
    for(int i=0;i<n;i++){
        cin >> x;
        cin >> y;
        int lenx = (int)x.length();
        int leny = (int)y.length();
        //cout << lenx << " " << leny << endl;
        ans = dfs(lenx,leny);
        cout << ans << endl;
        for(int j=0;j<1001;j++){
            for(int k=0;k<1001;k++){
                dp[j][k] = null;
            }
        }
    }
    return 0;

}

C++: #include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (int)(n); i++)
#define rrep(ri,n) for(int ri = (int)(n-1); ri >= 0; ri--)
#define rep2(i,x,n) for(int i = (int)(x); i < (int)(n); i++)
#define repit(itr,x) for(auto itr = x.begin(); itr != x.end(); itr++)
#define rrepit(ritr,x) for(auto ritr = x.rbegin(); ritr != x.rend(); ritr++)
#define ALL(n) begin(n), end(n)
using ll = long long;
using namespace std;

int main(){
  int q;
  cin >> q;
  rep(i, q){
    string a, b;
    cin >> a >> b;
    vector<vector<int>> dp(b.size()+1, vector<int>(a.size()+1));
    rep(i, b.size()+1){
      rep(j, a.size()+1){
        if(i == 0 || j == 0){
          dp.at(i).at(j) = 0;
          continue;
        }
        if(a.at(j-1) == b.at(i-1)) dp.at(i).at(j) = dp.at(i-1).at(j-1) + 1;
        else dp.at(i).at(j) = max(dp.at(i-1).at(j), dp.at(i).at(j-1));
      }
    }
    cout << dp.at(b.size()).at(a.size()) << endl;
  }
  return 0;
}

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

int main()
{
	int n;
	string a, b;

	while (n--)
	{
		int memo1[1005] = {};
		int memo2[1005] = {};
		cin >> a >> b;

		for (int i = 1; i <= a.size(); i++)
		{
			memo2[0] = 0;
			for (int j = 1; j <= b.size(); j++)
			{
				if (a[i] == b[j])
					memo2[j] = max({ memo2[j - 1], memo1[j], memo1[j - 1] + 1 });
				else
					memo2[j] = max(memo2[j - 1], memo1[j]);
			}
			swap(memo1, memo2);
		}

		cout << memo1[b.size()] << endl;
	}

	return 0;
}

C++: #include<iostream>
#include<cstdio>
#include<cstdlib>
#include<string.h>

using namespace std;


int main(){
  int n;
  cin >> n;

  for(int i = 0; i < n; i++){
    char x[1000], y[1000];
    cin >> x >> y;
    int c[strlen(x) + 2][strlen(y) + 2];
    for(int j = 0; j <= strlen(x);j++) c[j][0] = 0;
    for(int j = 0; j <= strlen(y);j++) c[0][j] = 0;


    for(int j = 1; j <= strlen(x); j++){
      for(int k = 1; k <= strlen(y); k++){
        if(x[j - 1] == y[k - 1]) c[j][k] = c[j - 1][k - 1] + 1;
        else c[j][k] = max(c[j][k - 1], c[j - 1][k]);
      }
    }
    cout << c[strlen(x)][strlen(y)] << endl;

  }

  return 0;
}