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(){
	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] = 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 <iostream>
#include <string>
#include <algorithm>
using namespace std;

int main()
{
	int q, t1, t2;
	string s1, s2;
	const int maxS = 1000;
	int m[maxS][maxS];

	cin >> q;

	for (int i = 0; i < q; i++) {

		for (int i = 0; i < maxS; i++)
			for (int j = 0; j < maxS; j++)
				m[i][j] = 0;

		cin >> s1 >> s2;

		t1 = s1.size() - 1;
		t2 = s2.size() - 1;

		if (s1[0] == s2[0])
			m[0][0] = 1;

		for (int i = 0; i < t1; i++) {
			int f = 0;
			if (s1[i + 1] == s2[0])
				f = 1;
			m[i + 1][0] = max(m[i][0], f);
		}

		for (int j = 0; j < t2; j++) {
			int f = 0;
			if (s2[j + 1] == s1[0])
				f = 1;
			m[0][j + 1] = max(m[0][j], f);
		}

		for (int i = 0; i < t1; i++) {
			for (int j = 0; j < t2; j++) {
				if (s1[i + 1] == s2[j + 1])
					m[i + 1][j + 1] = m[i][j] + 1;
				else
					m[i + 1][j + 1] = max(m[i][j + 1], m[i + 1][j]);
			}
		}

		cout << m[t1][t2] << endl;
	}
	return 0;
}

C++: #include<iostream>
#include<string>
#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();
	int n=y.size();
	int max1=0;
	x=" "+x;
	y=" "+y;
	for(int i=0;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]);
			}
			max1=max(max1,c[i][j]);
		}
	}
	return max1;
}
int main(){
	string s1,s2;
	int n;
	std::cin>>n;
	for(int i=0;i<n;i++){
		std::cin>>s1>>s2;
		std::cout<<lcs(s1,s2)<<"\n";
	}
	return 0;
}

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

int lcs(string str1, string str2)
{
  int m = str1.size(), n = str2.size();
  int c[1001][1001];
  str1 = ' ' + str1;
  str2 = ' ' + str2;
  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 (str1[i] == str2[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 q;
  cin >> q;
  while (q--){
    string str1, str2;
    cin >> str1 >> str2;
    cout << lcs(str1, str2) << endl;
  }
}

C++: #include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define MM 1000000000
#define MOD MM+7
#define MAX 301000
#define MAP 110
#define initial_value -1
#define Pair pair<int,int>
#define chmax(a,b) (a<b ? a=b:0)
#define chmin(a,b) (a>b ? a=b:0)
ll INF = 1e18;
int dx[4] = {-1,0,1,0};
int dy[4] = {0,-1,0,1};
//union_find
int par[100];
int depth[100];
ll N;
ll x[20],c[20],v[20];
string s,t;

int lcs(string x, string y){
    int dp[1010][1010];
    int m = x.size();
    int n = y.size();
    int mx = 0;
    x = ' ' + x;
    y = ' ' + y;
    for(int i = 0; i <= m; i++){
        for(int j = 0; j <= n; j++){
            dp[i][j] = 0;
        }
    }
    for(int i = 1; i <= m; i++){
        for(int j = 1; j <= n; j++){
            if(x[i] == y[i]){
                dp[i][j] = dp[i-1][j-1] + 1;
            } else {
                dp[i][j] = max(dp[i-1][j], dp[i][j-1]);
            }
            mx = max(mx, dp[i][j]);
        }
    }
    return mx;
}
int main(){
    cin >> N;
    for(int i = 0; i < N; i++){
        cin >> s >> t;
        cout << lcs(s,t) << endl;
    }
}

C++: #include <cstdio>
#include <iostream>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <string>
#include <vector>
#include <list>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <bitset>
#include <numeric>
#include <climits>
#include <cfloat>
#include <functional>
#include <cctype>

using namespace std;

#define REP(i,n) for(int i = 0; i < (int)n; ++i)

string X, Y;

void solve(int x_size, int y_size)
{
	vector< vector<int> > dp(x_size + 1, vector<int>(y_size + 1));

	for(int i = 0; i < x_size; ++i) {
		for(int j = 0; j < y_size; ++j) {
			if(X[i] == Y[j]) {
				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[X.size()][Y.size()] << endl;
}

int main()
{
	std::ios::sync_with_stdio(false);
	std::cin.tie(0);

	int n;
	cin >> n;
	REP(i, n) {
		cin >> X >> Y;
		solve(X.size(), Y.size());
	}
	return 0;
}

C++: #include<iostream>
#include<string>
#include <algorithm>
using namespace std;
string X;
string Y;
int lcs[1002][1002];
int calLcs() {
	int i = 1;
	int j = 1;
	int m = Y.size();
	int n = X.size();
	for (i = 1; i <= n; i++) {
		for (j = 1; j <= m; j++) {
			if (X[i - 1] == Y[j - 1]) {
				lcs[i][j] = lcs[i - 1][j - 1] + 1;
			}
			else {
				lcs[i][j] = max(lcs[i - 1][j], lcs[i][j - 1]);
			}
		}
	}
	return lcs[n][m];
}
int main() {
	int n;
	cin >> n;
	while (n--) {
		cin >> X;
		cin >> Y;
		cout << calLcs() << endl;
	}
}

C++: #include <cstdio>
#include <iostream>
#include <algorithm>
#include <cstring>
using namespace std;
int main(){
  char str1[1000],str2[1000];
  int LCS[1000][1000]={0};
  int length1,length2;
  int n;
  std::ios::sync_with_stdio(false);
  scanf("%d",&n);
  for(int s=1;s<=n;s++){
   while(cin>>str1>>str2){
     length1=strlen(str1);
     length2=strlen(str2);
     for(int i=0;i<=length1-1;i++){
       LCS[i][0]=0;
     }
     for(int j=0;j<=length2-1;j++){
       LCS[0][j]=0;
     }
     for(int i=1;i<=length1;i++){
       for(int j=1;j<=length2;j++){
         if(str1[i-1]==str2[j-1]) {
           LCS[i][j]=LCS[i-1][j-1]+1;
         }
         else LCS[i][j]=max(LCS[i-1][j],LCS[i][j-1]);
       }
     }
     printf("%d\n",LCS[length1][length2]);
   }
 }
   return 0;
}

C++: q = int(input())
for i in range(q):
    x = input()
    y = input()
    n = len(x)
    m = len(y)
    dp = [0]*((n+1)*(m+1))
    for i in range(n):
        for j in range(m):
            a = (n+1)*(j+1)+i+1
            if x[i] == y[j]:
                b = (n+1)*j+i
                dp[a] = dp[b]+1
            else:
                c = (n+1)*j+i+1
                d = (n+1)*(j+1)+i
                dp[a] = max(dp[c],dp[d])
    print(dp[-1])