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 <algorithm>

#define MAX 1000

using namespace std;


int m[MAX + 2][MAX + 2];
int lcs(string x, string y)
{
    for (int i = 0; i <= y.length(); i++)
        for (int j = 0; j <= x.length(); j++)
            m[i][j] = 0;

    for (int i = 1; i <= y.length(); i++) {
        for (int j = 1; j <= x.length(); j++) {
            if (x[j - 1] == y[i - 1]) {
                m[i][j] = m[i - 1][j - 1] + 1;
            } else {
                m[i][j] = max(m[i - 1][j], m[i][j - 1]);
            }
        }
    }

    return m[y.length()][x.length()];
}

int main()
{
    int n;
    cin >> n;
    for (int i = 0; i < n; i++) {
        string x, y;
        cin >> x >> y;
        cout << lcs(x, y) << endl;
    }
}

C++: #include<iostream>
#include<vector>
#include<algorithm>
#include<string>
#include<cstdlib>
#include <cmath>
#include<stdio.h>
#include<queue>
#define MAX 1000000000000000000LL
long long inf=1000000007;
using namespace std;
    int H,A[2000001];

int lcs(string X,string Y){
    int  c[1001][1001];
    long long m=X.size();
    long long  n=Y.size();
    int maxl=0;
    X=' '+X;
    Y=' '+Y;
    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(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>
#include <algorithm>
    using namespace std;
int lcs(string x,string y){
    int c[1010][1010];
    int m = x.size();
    int n = y.size();
    int maxl=0;
    x = ' '+x;
    y = ' '+y;
    for (int i=1; 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]);
            maxl = max(maxl, c[i][j]);
        }
        
    }
    return maxl;
}
int main(){
    int q;
    string x;
    string y;
    scanf("%d",&q);
    for (int i=0; i<q; i++) {
        cin>>x>>y;
        cout<<lcs(x, y)<<endl;
    }
    return 0;
}

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

#define MAX 1000

int lcs(string X, string Y) {
    int c[MAX+1][MAX+1];
    int m = X.size();
    int n = Y.size();
    int i, j;
    int maxlen = 0;
    X = " " + X;
    Y = " " + Y;

    for (i = 1 ; i <= m ; i++ ) c[i][0] = 0;
    for (j = 1 ; j <= n ; j++ ) c[0][j] = 0;

    for(i = 1 ; i <= m ; i++ ) {
        for(j = 1 ; j <= n ; j++ ) {
            if (X[i] == Y[j]) {
                c[i][j] = c[i-1][j-1] + 1;
            }else if( c[i-1][j] >= c[i][j-1] ) {
                c[i][j] = c[i-1][j];
            }else {
                c[i][j] = c[i][j-1];
            }
            maxlen = max(maxlen, c[i][j]);
        }
    }
    return maxlen;
}

int main (void) {
    int N, i;
    string x, y;
    

    cin >> N;

    for(i = 0 ; i < N ; i++) {
        cin >> x;
        cin >> y;
        cout << lcs(x, y) << 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 maxl = 0;
    X = ' ' + X; //X[0]???????????????????????\
    Y = ' ' + Y;
    for(int i = 1; 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]);
            }
            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>
#include <iostream>
#include <math.h>
using namespace std;

int lcs(string x, string y) {
    int _lcs = 0;
    int x_size = x.size();
    int y_size = y.size();
    int dp[x_size + 1][y_size + 1];
    for (int i=0; i <= x_size; i++) {
        dp[i][0] = 0;
    }

    for (int j=0; j <= y_size; j++) {
        dp[0][j] = 0;
    }

    for (int i=1; i <= x_size; i++) {
        for (int j=1; j <= y_size; j++) {
            if (x[i-1] == y[j-1]) {
                dp[i][j] = dp[i-1][j-1] + 1;
            } else {
                dp[i][j] = max({dp[i][j-1], dp[i-1][j]});
            }
        }
    }

    return dp[x_size][y_size];
}
int main() {
    int q;
    cin >> q;
    for (int i=0; i < q; i++) {
        string x, y;
        cin >> x >> y;
        cout << lcs(x, y) << endl;
    }

    return 0;
}

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

int main(){
  
  int q, lcs[1010][1010] = {};
  string a, b;
  
  cin >> q;
  for(int i = 0;i < q;i++){
    cin >> a;
    cin >> b;
    
    for(int r = 0;r < a.size();r++){
      for(int c = 0;c < b.size();c++){
        if(a[r] == b[c]) lcs[r + 1][c + 1] = lcs[r][c] + 1;
        else lcs[r + 1][c + 1] = max(lcs[r + 1][c], lcs[r][c + 1]);
      }
    }
    
    cout << lcs[a.size()][b.size()] << endl;
  }
  
  return 0;
}