Go: package main

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

// I/O
type Scanner struct {
	sc *bufio.Scanner
}

func NewScanner() *Scanner {
	sc := bufio.NewScanner(os.Stdin)
	sc.Split(bufio.ScanWords)
	sc.Buffer(make([]byte, 1024), int(1e+9))
	return &Scanner{sc}
}

func (s *Scanner) nextStr() string {
	s.sc.Scan()
	return s.sc.Text()
}

func (s *Scanner) nextInt() int {
	i, e := strconv.Atoi(s.nextStr())
	if e != nil {
		panic(e)
	}
	return i
}

func (s *Scanner) nextFloat() float64 {
	f, e := strconv.ParseFloat(s.nextStr(), 64)
	if e != nil {
		panic(e)
	}
	return f
}

func (s *Scanner) nextRuneSlice() []rune {
	return []rune(s.nextStr())
}

func (s *Scanner) nextIntSlice(n int) []int {
	res := make([]int, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextInt()
	}
	return res
}

func (s *Scanner) nextFloatSlice(n int) []float64 {
	res := make([]float64, n)
	for i := 0; i < n; i++ {
		res[i] = s.nextFloat()
	}
	return res
}

// Arithmetic
func max(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m < i {
			m = i
		}
	}
	return m
}

func min(nums ...int) int {
	m := nums[0]
	for _, i := range nums {
		if m > i {
			m = i
		}
	}
	return m
}

func abs(x int) int {
	if x > 0 {
		return x
	}
	return -x
}

func pow(x, y int) int {
	res := 1
	for i := 0; i < y; i++ {
		res *= x
	}
	return res
}

func ceil(a, b int) int {
	if a%b == 0 {
		return a / b
	} else {
		return a/b + 1
	}
}

// Sort
type RuneSlice []rune

func (a RuneSlice) Len() int           { return len(a) }
func (a RuneSlice) Less(i, j int) bool { return a[i] < a[j] }
func (a RuneSlice) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }

// Main
func main() {
	sc := NewScanner()
	wtr := bufio.NewWriter(os.Stdout)
	Q := sc.nextInt()
	for q := 0; q < Q; q++ {
		X, Y := sc.nextStr(), sc.nextStr()
		xLen, yLen := len(X), len(Y)
		dp := make([][]int, xLen+1)
		for i := 0; i <= xLen; i++ {
			dp[i] = make([]int, yLen+1)
		}
		for x := 0; x <= xLen; x++ {
			for y := 0; y <= yLen; y++ {
				if x == 0 || y == 0 {
					dp[x][y] = 0
				} else if X[x-1] == Y[y-1] {
					dp[x][y] = dp[x-1][y-1] + 1
				} else {
					dp[x][y] = max(dp[x-1][y], dp[x][y-1])
				}
			}
		}
		fmt.Fprintln(wtr, dp[xLen][yLen])
	}

	wtr.Flush()
}

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 maxl=0;
    X = ' ' + X; // X[0]に空白を挿入
    Y = ' ' + Y;
    for (int i=0; i<m; i++) C[i][0] = 0;
    for (int j=0; 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][j-1], C[i-1][j]);
            }
            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 "bits/stdc++.h"

using namespace std;

using ll = long long;
using ld = long double;
using P = pair<string, int>;
constexpr ld EPS = 1e-12;
constexpr int INF = numeric_limits<int>::max() / 2;
constexpr int MOD = 1e9 + 7;

template <typename T>
void printv(const vector<T> &v)
{
    int sz = v.size();
    for (int i = 0; i < sz; i++)
    {
        cout << v[i] << " \n"[i == sz - 1];
    }
}

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

    int q;
    cin >> q;
    while (q--)
    {
        string s, t;
        cin >> s >> t;
        int n = s.length(), m = t.length();
        s = "$" + s;
        t = "$" + t;
        vector<vector<int>> dp(n + 1, vector<int>(m + 1, 0));
        for (int i = 1; i <= n; i++)
        {
            for (int j = 1; j <= m; j++)
            {
                if (s[i] == t[j])
                    dp[i][j] = dp[i - 1][j - 1] + 1;
                else
                {
                    dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]);
                }
            }
        }
        cout << dp[n][m] << endl;
    }
}

C++: #include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<n;i++)
int main(){
    int n;
    cin >> n;
    rep(i,n){
        string a,b;
        cin >> a >> b;
        int n1 = a.size();
        int n2 = b.size();
        int dp[n1+1][n2+1];
        rep(i,n1+1)rep(j,n2+1)dp[i][j] = 0;
        rep(i,n1)rep(j,n2){
            if(a[i] == b[j]&&dp[i+1][j] == dp[i][j+1]&&dp[i][j] ==dp[i+1][j])dp[i+1][j+1] = dp[i+1][j]+1;
            else dp[i+1][j+1] = max(dp[i+1][j],dp[i][j+1]);
        }
        cout << dp[n1][n2] << endl;
    }
    return 0;
}

C++: #include <iostream>
#include <string>
#include <cstdio>
#include <vector>
#include <queue>
#include <map>
using namespace std;

int charCode(char charactor) {
	if(charactor>='a' && charactor <= 'z') return (int)(charactor-'a');
	else return (int)(charactor-'A'+26);
}

bool findSubStr(string& shortword, vector<vector<int> >& charMap) {
	int i,j=0;
	for(i=0; i<(int)shortword.size(); ++i) {
		if(charMap[charCode(shortword[i])].empty()) return false;
		auto itr=charMap[charCode(shortword[i])].begin();
		while(itr!=charMap[charCode(shortword[i])].end()) {
			if(*itr<j) {
				++itr;
			} else {
				break;
			}
		}
		if(itr==charMap[charCode(shortword[i])].end()) return false;
		j=1+*itr;
	}
	return true;
}

int longestSQ(string& shortword, string& longword) {
	int i,j;
	string tempstr,prestr;
	vector<vector<int> > charMap(52);
	queue<string> targetword;
	map<string,bool> inqueue;
	for(i=0; i<(int)longword.size(); ++i) {
		charMap[charCode(longword[i])].push_back(i);
	}
	targetword.push(shortword);
	while(!targetword.empty()) {
		tempstr=targetword.front();
		if(findSubStr(tempstr,charMap)) return (int)tempstr.size();
		j=(int)tempstr.size();
		for(i=0; i<j; ++i) {
				tempstr=targetword.front();
				if(i==0 || tempstr[i]!=tempstr[i-1]) {
					tempstr.erase(tempstr.begin()+i);
					if(inqueue.find(tempstr)==inqueue.end()) {
						targetword.push(tempstr);
						inqueue[tempstr]=true;
					}
				}
		}
		targetword.pop();
	}
	return 0;
}

int main() {
	int i,q;
	cin >> q;
	string wordA,wordB;
	for(i=0; i<q; ++i) {
		cin >> wordA >> wordB;
		if(wordA.size()<wordB.size()) {
			printf("%d\n",longestSQ(wordA,wordB));
		} else {
			printf("%d\n",longestSQ(wordB,wordA));
		}
	}
	return 0;
}

C++: #include<bits//stdc++.h>
using namespace std;
int dp[160][1010][1010];


int main(){
    int q;
    cin >> q;
    string a[q],b[q];
    for(int i = 0; i < q; i++){
        cin >> a[i] >> b[i]; 
    }

    for(int i = 0; i < q; i++){
        for(int j = 0; j < a[i].size(); j++){
            for(int k = 0; k < b[i].size(); k++){
                dp[i][j][k] = 0;
            }
        } 
    }


    int match = 0;
    int value = 0;
    for(int i = 0; i < q; i++){
        for(int j = 1; j < a[i].size() + 1; j++){
            for(int k = 1; k < b[i].size() + 1; k++){
                if(a[i][j - 1] == b[i][k - 1]) match = 1;
                else match = 0;
                value = max({dp[i][j - 1][k - 1] + match, dp[i][j - 1][k], dp[i][j][k - 1]});
                dp[i][j][k] = value;
            }
        } 
    }
    for(int i = 0; i < q; i++){
        cout << dp[i][a[i].size()][b[i].size()] << endl;
    }
    return 0;
}