Go: package main

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

func getScanner(fp *os.File) *bufio.Scanner {
	scanner := bufio.NewScanner(fp)
	scanner.Split(bufio.ScanWords)
	scanner.Buffer(make([]byte, 500001), 500000)
	return scanner
}

func getNextString(scanner *bufio.Scanner) string {
	scanner.Scan()
	return scanner.Text()
}

func getNextInt(scanner *bufio.Scanner) int {
	i, _ := strconv.Atoi(getNextString(scanner))
	return i
}

func main() {
	fp := os.Stdin
	if len(os.Args) > 1 {
		fp, _ = os.Open(os.Args[1])
	}

	scanner := getScanner(fp)
	writer := bufio.NewWriter(os.Stdout)

	n := getNextInt(scanner)
	for i := 0; i < n; i++ {
		x := getNextString(scanner)
		y := getNextString(scanner)

		fmt.Fprintln(writer, lcs(x, y))
	}

	writer.Flush()
}

func lcs(x, y string) int {
	lx := len(x)
	ly := len(y)
	dp := make([][]int, lx+1)
	for i := 0; i <= lx; i++ {
		dp[i] = make([]int, ly+1)
	}
	for i := 0; i < lx; i++ {
		for ii := 0; ii < ly; ii++ {
			if x[i] == y[ii] {
				dp[i+1][ii+1] = dp[i][ii] + 1
				continue
			}
			dp[i+1][ii+1] = dp[i][ii+1]
			if dp[i+1][ii] > dp[i+1][ii+1] {
				dp[i+1][ii+1] = dp[i+1][ii]
			}
		}
	}
	return dp[lx][ly]
}

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

int main(void){
  string st1, st2;
  int q, val[1001][1001];

  cin >> q;

  for(int i=0; i<q; i++){
    cin>>st1;
    cin>>st2;

    for(int j=0; j<=st1.length(); j++){
      for(int k=0; k<=st2.length(); k++){

	if(j==0 || k==0) val[j][k] = 0;
	else{
	  if(val[j-1][k] == min(st1.length(), st2.length())){
	    val[j][k] = st1.length();
	  }else{

	    if(st1[j-1] == st2[k-1]){
	      val[j][k] = val[j-1][k-1]+1;
	    }else{
	      val[j][k] = max(val[j-1][k], val[j][k-1]);
	    }
	  }
	}
      }
    }

    /*
      for(int j=0; j<=st1.length(); j++){
      for(int k=0; k<=st2.length(); k++){
      cout << val[j][k] << " ";
      }
      cout << "\n";
      }
    */

    cout << val[st1.length()][st2.length()] << "\n";
  }

  return 0;
}

C++: #include <iostream>

using namespace std;
const int MAX = 1001;

short max(short a,short b) {
	if (a > b) {
		return a;
	} else {
		return b;
	}
}
short solve(string str1,string str2) {
	int len1 = str1.length();
	int len2 = str2.length();
	str1 = " " + str1;
	str2 = " " + str2;
	short LCS[MAX][MAX];
	for (int i=0;i<len1;i++) {
		LCS[i][0] = 0;
	}
	for (int i=0;i<len2;i++) {
		LCS[0][i] = 0;
	}
	int max1 = 0;

	for (int i=1;i<=len1;i++) {
		for (int j = 1;j<=len2;j++) {
			if (str1[i] == str2[j]) {
				LCS[i][j] = LCS[i-1][j-1] + 1;
			} else {
				LCS[i][j] = max(LCS[i-1][j],LCS[i][j-1]);
			}
			max1 = max(LCS[i][j],max1);
		}
	}
	return max1;
}

int main() {
	int n;
	cin >> n;
	for (int i=0;i<n;i++) {
		string str1,str2;
		cin >> str1 >> str2;
		cout << solve(str1,str2) << endl;
	}
	return 0;

}

C++: #include <iostream>
#include <algorithm>
#include <vector>
#include <deque>
#include <queue>
#include <list>
#include <stack>
#include <string>
#include <tuple>
#include <functional>
#include <numeric>
#include <cmath>
#include <iomanip>
#include <map>
#include <random>
#include <cstdlib>
#define INT_MAX 2147483647
#define INT_MIN -2147483646
#define Loop(i, n) for(int i = 0; i < (int)n; i++)
#define Loop1(i, n) for(int i = 1; i <= (int)n; i++)
#define Loopr(i, n) for(int i = (int)n - 1; i >= 0; i--)
#define Loopr1(i, n) for(int i = (int)n; i >= 1; i--)
using namespace std;
typedef long long int ll;

string x, y;
int memo[1005][1005];

int dp(int a, int b) {
	if (memo[a][b] != INT_MIN) return memo[a][b];
	if (a == 0 || b == 0) memo[a][b] = 0;
	else if (x[a - 1] == y[b - 1]) {
		memo[a][b] = dp(a - 1, b - 1) + 1;
	}
	else {
		memo[a][b] = max(dp(a - 1, b), dp(a, b - 1));
	}
	return memo[a][b];
}

int main() {
	int q;
	cin >> q;
	Loop(i, q) {
		cin >> x >> y;
		Loop(j, x.size()+1) {
			Loop(k, y.size()+1) {
				memo[j][k] = INT_MIN;
			}
		}
		cout << dp(x.size(), y.size()) << endl;
	}
	return 0;
}

C++: #include <cstdio>
#include <algorithm>
#include <vector>
#include <string>

using namespace std;

template <class RandomIt>
size_t lcsubsequence(
    RandomIt first1, RandomIt last1, RandomIt first2, RandomIt last2
) {
    vector<vector<size_t>> dp(last1-first1+1, vector<size_t>(last2-first2+1));
    for (RandomIt it=first1; it<last1; ++it)
        for (RandomIt it2=first2; it2<last2; ++it2) {
            if (*it == *it2) {
                dp[it-first1+1][it2-first2+1] = dp[it-first1][it2-first2] + 1;
            } else {
                dp[it-first1+1][it2-first2+1] = max(
                    dp[it-first1][it2-first2+1], dp[it-first1+1][it2-first2]
                );
            }
        }

    return dp[last1-first1][last2-first2];
}

int main() {
    size_t q;
    scanf("%zu", &q);

    for (size_t i=0; i<q; ++i) {
        char buf[1<<10];
        scanf("%s", buf);
        string X(buf);

        scanf("%s", buf);
        string Y(buf);

        printf("%zu\n", lcsubsequence(X.begin(), X.end(), Y.begin(), Y.end()));
    }

    return 0;
}

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

using namespace std;

string s1, s2;

int lcs() {
  int i, j;
  int dp[s1.length()+1][s2.length()+1] = {};
  
  for(i = 1; i <= s1.length(); i++) {
    for(j = 1; j <= s2.length(); j++) {
      if(s1[i-1] == s2[j-1])
	dp[i][j] = dp[i-1][j-1]+1;
      else
	dp[i][j] = max(dp[i-1][j], dp[i][j-1]);
    }
  
  }
  return dp[s1.length()][s2.length()];
}

int main(){
  int n;
  cin >> n;
  while(n--) {
    cin >> s1 >> s2;
    cout << lcs() << endl;
  }
  
  return 0;
}

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

#define REP(i, n) for(int i=0;i<(int)(n);i++)
#define ALL(x) (x).begin(),(x).end()
const int INF = 1e9;

using namespace std;
int dp[1005][1005];

void dfs(int i, int j, string q, string b){
    int x = j;
    string tar = b.substr(x, 1);
    while(x < b.length() && q != tar){
        x++;
        tar = b.substr(x, 1);
    }
    if(i == 0){
        while(x < b.length()){
            x++;
            dp[i][x] = 1;
        }
        return;
    }
    while(x < b.length()){
        x++;
        dp[i][x] = max(dp[i-1][j] + 1, dp[i][x]);
    }
    dp[i][j] = max(dp[i][j], dp[i-1][j]);
    return;
}

int main() {
    int n; cin >> n;
    REP(k, n){
        REP(i, 1005) REP(j, 1005) dp[i][j] = 0;
        string a, b;
        cin >> a >> b;
        REP(i, a.length()){
            string q = a.substr(i, 1);
            REP(j, b.length()+1) dfs(i, j, q, b);
        }
        cout << dp[a.length()-1][b.length()] << endl;
    }
    return 0;
}

C++: #include <bits/stdc++.h>
#define ALL(A) (A).begin(), (A).end()
#define ll long long
#define rep(i, n) for (int i = 0; i < (n); i++)

using namespace std;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }

const ll mod = 1e9 + 7;
const ll INF = -1 * ((1LL << 63) + 1);
const int inf = -1 * ((1 << 31) + 1);

int main(void){
    cin.tie(0);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(20);
    string s,t;
    int n,m,q;
    cin >> q;
    rep(_,q){
        cin >> s >> t;
        int n = s.size();
        int m = t.size();
        // dp[i][j] := sをi文字目まで見てtをj文字目まで見た時の最大の共通部分列の長さ
        vector<vector<int>> dp(n+1,vector<int>(m+1));
        for(int i=0;i<n;i++){
            for(int j=0;j<m;j++){
                if(s[i]==t[j]){
                    dp[i+1][j+1] = dp[i][j] + 1;
                }
                chmax(dp[i+1][j+1],max(dp[i][j+1],dp[i+1][j]));
            }
        }
        cout << dp[n][m] << endl;
    }
}