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 <bits/stdc++.h>
using namespace std;

int main() {
   int q;
   cin >> q;
   for (int i=0; i<q; i++) {
       string X,Y;
       cin >> X >> Y;
       int x=X.size();
       int y=Y.size();
       int dp[x][y];
       for (int j=0; j<x; j++) {
           for (int k=0; k<y; k++) {
               dp[j][k]=0;
           }
       }
       for (int j=0; j<x; j++) {
           for (int k=0; k<y; k++) {
               if (j==0) {
                   if (X[0]==Y[k]) dp[0][k]=1;
                   else dp[0][k]=dp[0][k-1];
                   continue;
               }
               if (k==0) {
                   if (X[j]==Y[0]) dp[j][0]=1;
                   else dp[j][0]=dp[j-1][0];
                   continue;
               }
               if (X[j]==Y[k]) dp[j][k]=max(dp[j-1][k-1]+1,max(dp[j-1][k],dp[j][k-1]));
               else dp[j][k]=max(dp[j-1][k],dp[j][k-1]);
           }
       }
       cout << dp[x-1][y-1] << endl;
   }
}

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

#include <string.h>

using namespace std;

typedef long long ll;

template<class T>
inline bool chmax(T &a, T b) {
    if(a < b) {
        a = b;
        return true;
    }
    return false;
}

template<class T>
inline bool chmin(T &a, T b) {
    if(a > b) {
        a = b;
        return true;
    }
    return false;
}

const int MAX_S = 1000;

int solve(int (*dp)[MAX_S + 1][MAX_S + 1],
        const char *x, const int xlen, const char *y, const int ylen) {
    for (int i = 1; i <= ylen; i++) {
        for (int j = 1; j <= xlen; j++) {
            chmax((*dp)[i][j], (*dp)[i - 1][j]);
            chmax((*dp)[i][j], (*dp)[i][j - 1]);
            if (y[i - 1] == x[j - 1]) {
                chmax((*dp)[i][j], (*dp)[i - 1][j - 1] + 1);
            }
        }
    }
    return (*dp)[ylen][xlen];
}

int main(void) {
    int Q;
    char X[1010], Y[1010];
    cin >> Q;

    for (int i = 0; i < Q; i++) {
        int xlen, ylen;
        int dp[MAX_S + 1][MAX_S + 1];

        cin >> X >> Y;
        xlen = strlen(X);
        ylen = strlen(Y);
        reverse((char *) &X, X + xlen);
        reverse((char *) &Y, Y + ylen);

        for (int i = 0; i <= ylen; i++) {
            for (int j = 0; j <= xlen; j++) {
                dp[i][j] = 0;
            }
        }

        cout << solve(&dp, X, xlen, Y, ylen) << endl;
    }
    
    return 0;
}

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

int main()
{
  int n;
  cin >> n;
  for (int k = 0; k < n; k++)
  {
    string X, Y;
    cin >> X >> Y;
    int N = X.size(), M = Y.size();
    vector<vector<int>> dp(N + 1, vector<int>(M + 1, 0));
    for (int i = 0; i < N; i++)
    {
      for (int j = 0; j < M; j++)
      {
        dp[i + 1][j + 1] = max(dp[i + 1][j], dp[i][j + 1]);
        if (X[i] == Y[j])
        {
          dp[i + 1][j + 1] = max(dp[i + 1][j + 1], dp[i][j] + 1);
        }
      }
    }
    cout << dp[N][M] << endl;
  }
}

C++: #include<iostream>
#include<cstring>
#include<cstdio>
#include<cstdlib>
#define xs 1000+5
#define ys 1000+5
using namespace std;
int l[xs][ys];
void lcs(string a,string b){
	int a_size=a.size();int b_size=b.size();
	a=' '+a;b=' '+b;
	for(int i=0;i<=a.size();i++){
		l[i][0]=0;
	}
	for(int i=0;i<=b.size();i++){
		l[0][i]=0;
	}
	for(int i=1;i<=a.size();i++){
		for(int j=1;j<=b.size();j++){
			if(a[i]==b[j]) {
				l[i][j]=l[i-1][j-1]+1;
			}else{
				l[i][j]=max(l[i-1][j],l[i][j-1]);
			}
		}
	}
}
int main(){
	int num;
	scanf("%d",&num);string a,b;
	for (int i=0;i<num;i++){
		
		cin>>a>>b;
		lcs(a,b);
		cout<<l[a.size()][b.size()]<<'\n';
	}
	
}

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

string s, t;
int dp[1000][1000];

void solve() {
    cin >> s >> t;
    for (int i = 0; i < s.size(); i++) {
        for (int j = 0; j < t.size(); j++) {
            dp[i][j] = (i < 1 || j < 1 ? 0 : dp[i-1][j-1]) + (s[i] == t[j] ? 1 : 0);
            int a = (i < 1 ? 0 : dp[i-1][j]);
            int b = (j < 1 ? 0 : dp[i][j-1]);
            dp[i][j] = max(dp[i][j], max(a, b));
        }
    }

    cout << dp[s.size()-1][t.size()-1] << endl;
}

int main() {
    int n;
    cin >> n;
    while (n--) solve();

    return 0;
}

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

int main(){
	int q;
	scanf(" %d", &q);
	for(int i=0; i<q; ++i){
		string x, y;
		cin >> x >> y;
		
		int c[1001][1001];
		int m=x.size(), n=y.size();
		
		for(int i=0; i<=m; ++i) c[i][0]=0;
		for(int i=0; i<=n; ++i) c[0][n]=0;
		
		for(int i=1; i<=m; ++i){
			for(int j=1; j<=m; ++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]);		
			}
		}
		
		printf("%d\n", c[m][n]);
	}
}

C++: #include<stdio.h>
#include<string>
#include<algorithm>
using namespase 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;
  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;
}