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 <algorithm>
#include<iostream>
#include<vector>
#include<list>
#include<map>
#include<set>
#include<string>
#include <sstream>

#include<stdlib.h>
#include<string.h>
#include<math.h>
#include<limits.h>
using lll = long long;
using ull = unsigned long long;
using namespace std;
int dp[1001][1001];
int lcs(string x,string y){
  int m,n;
  lll ii,jj,kk;
  
  m = x.size();
  n = y.size();
  memset(dp,0,sizeof(dp));
  int maxl = 0;

  for(ii=0;ii<m;ii++){
    for(jj=0;jj<n;jj++){
      if(x[ii] == y[jj]){
        dp[ii+1][jj+1] = dp[ii][jj] + 1;
      }
      else{
        dp[ii+1][jj+1] = max(dp[ii][jj+1],dp[ii+1][jj]);
      }

      maxl = max(maxl,dp[ii+1][jj+1]);
      
    }
  }
  return maxl;
}

int main(){
  lll ii,jj,kk;
  vector<int> ret;
  int q;
  string x,y;

  cin >> q;

  for(ii=0;ii<q;ii++){
    cin >> x >> y;
    cout << lcs(x,y) << endl;
  }

  return 0;
}

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

static const int N = 100;

int main() {
  int n, p[N + 1], m[N + 1][N + 1];
  cin >> n;
  for ( int i = 1; i <= n; i++ ) {
    cin >> p[i - 1] >> p[i];
  }

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

  for ( int l = 2; l <= n; l++ ) {
    for ( int i = 1; i <= n - l + 1; i++ ) {
      int j = i + l - 1;
      m[i][j] = (1 << 21);
      for ( int k = i; k <= j - 1; k++ ) {
        m[i][j] = min(m[i][j], m[i][k] + m[k + 1][j] + p[i - 1] * p[k] * p[j]);
      }
    }
  }

  cout << m[1][n] << endl;

  return 0;
}

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

int preX[1020][55];
int dp[1020];

int main() {
	int q;
	cin >> q;
	for(int t = 0; t < q; t++) {
		string X, Y;
		for(int i = 0; i < 1020; i++) {
			for(int j = 0; j < 55; j++) {
				preX[i][j] = 0;
			}
			dp[i] = 0;
		}
		cin >> X >> Y;
		for(int i = 0; i < X.size(); i++) {
			for(int j = 0; j < 55; j++) {
				preX[i+1][j] = preX[i][j];
			}
			if(i > 0) {
				if('a' <= X[i-1] && X[i-1] <= 'z')
					preX[i+1][X[i-1]-'a'] = i;
				else
					preX[i+1][X[i-1]-'A'] = i;
			}
		}
		for(int i = 0; i < Y.size(); i++) {
			for(int j = (int)X.size()-1; j >= 0; j--) {
				if(Y[i] == X[j])
					for(int k = 0; k < 55; k++)
						dp[j+1] = max(dp[j+1], dp[preX[j+1][k]] + 1);
			}
		}
		int res = 0;
		for(int i = 0; i < 1020; i++)
			res = max(res, dp[i]);
		cout << res << endl;
	}
}

C++: //compiledef
#include <bits/stdc++.h>
#define rep(i, n) for(i=0;i<(n);i++)
#define per(i, n) for(i=(n);i>0;i--)
#define repx(i, n, x) for(i=(x);i<(n);i++)
#define xper(i, n, x) for(i=(n);i>(x);i--)
#define pback push_back

//c++def
using namespace std;
typedef long long int ll;
const ll MOD = 1e9+7;
const ll MOD2 = 998244353;
int solve(string x, string y){
	int xl = x.length() - 1;
	int yl = y.length() - 1;
	int dp[1250][1250];
		for(int i=0;i<=xl;i++) dp[i][0] = 0;
		for(int i=1;i<=yl;i++) dp[0][i] = 0;
	if(x == y) return max(xl, yl);
	for(int i=1;i<=xl;i++){
		for(int j=1;j<=yl;j++){
			if(x[i] == y[j]) dp[i][j] = dp[i-1][j-1] +1;
			else dp[i][j] =max(dp[i-1][j], dp[i][j-1]);
		}
	}
	return dp[xl][yl];
}

int main(){
	int q;
	string x, y;
	int i;
	cin >> q;
	rep(i, q){
		cin >> x >> y;
		cout << solve(x = " " + x, y = " " + y) <<endl;
	}


}

C++: #include<bits/stdc++.h>
#define rep(i, n) for (int i=0; i<(n); i++)
#define ll long long
using namespace std;

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

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

constexpr int MAX_XY = 1000;

int lx, ly, q, dp[MAX_XY][MAX_XY];
std::string sx, sy;

void fill_dp(){
    for(int i = 1; i <= lx; ++i){
        for(int j = 1; j <= ly; ++j){
            if(sx[i] == sy[j]) dp[i][j] = dp[i - 1][j - 1] + 1;
            else dp[i][j] = std::max(dp[i - 1][j], dp[i][j - 1]);
        }
    }
}

void solve(){
    fill_dp();
    std::cout << dp[lx][ly] << std::endl;
    return;
}

int main(){
    std::cin >> q;
    
    for(int i = 0; i < q; ++i){
        std::cin >> sx >> sy;
        lx = sx.size(), ly = sy.size();
        solve();
    }
    return 0;
}

C++: #include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>

using namespace std;

int q;
char X[1000], Y[1000];
int dp[1001][1001];

int main(void) {

    scanf("%d", &q);

    for (int i = 0; i < q; ++i) {
        scanf("%s %s", X, Y);
        int xlen = strlen(X), ylen = strlen(Y);
        for (int x = 0; x < xlen; ++x) {
            for (int y = 0; y < ylen; ++y) {
                if (X[x] == Y[y]) {
                    dp[x + 1][y + 1] = dp[x][y] + 1;
                }
                else {
                    if (dp[x + 1][y] > dp[x][y + 1]) {
                        dp[x + 1][y + 1] = dp[x + 1][y];
                    }
                    else {
                        dp[x + 1][y + 1] = dp[x][y + 1];
                    }
                }
            }
        }
        printf("%d\n", dp[xlen][ylen]);
//        memset(dp, 0, sizeof(int)*1001*1001);
    }

    return 0;
}