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 = 100;

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);
		cout << endl;
	}
	return 0;
}

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

typedef vector<int> vi;

int main() {
	int n;
	cin >> n;

	string x, y;
	int t[1001][1001];

	while(n--) {
		cin >> x >> y;
		int xs = x.size(), ys = y.size();
		for (int i = 1; i <= xs; i++)
			for (int j = 1; j <= ys; j++) {
				t[i][j] = x[i - 1] == y[j - 1] ?
					t[i - 1][j - 1] + 1 :
					max(t[i - 1][j], t[i][j - 1]);
			}
		cout << t[xs][ys] << endl;
	}
}

C++: #include<iostream>
#include<cstdio>
#include<cstring>
#define _A_ true
using namespace std;
 
int main(){
  int n,AC=0,strA,strB;
  int dp[1010][1010];
  char *A = new char[1500];
  char *B = new char[1500];
 
  scanf("%d",&n);
  while(_A_){
    if(AC == n)break;
    scanf("%s",A);
    scanf("%s",B);
    for(int i=0;i<1010;i++)for(int j=0;j<1010;j++)dp[i][j]=0;
strA = strlen(A); 
strB = strlen(B);

    for(int i=0;i<strA;i++){
      for(int j=0;j<strB;j++){
    if(A[i] == B[j]){
      dp[i+1][j+1]=dp[i][j]+1;
    }
    else{
      if(dp[i+1][j] > dp[i][j+1]){
        dp[i+1][j+1]=dp[i+1][j];
      }
      else {
        dp[i+1][j+1] = dp[i][j+1];
      }
    }
      }
    }
    printf("%d\n",dp[strA][strB]);
    AC++;
  }
  delete [] A;
  delete [] B;
 
  return 0;
}

C++: #include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
const int N = 1010;
char A[N],B[N];
int dp[N][N];
void lcs(char A[],char B[]){
    int lenA = strlen(A+1);
    int lenB = strlen(B+1);
    
    for(int i=0;i<=lenA;i++){
        dp[i][0] = 0;
    }
    for(int i=0;i<lenB;i++){
        dp[0][i] = 0;
    }
    for (int i=1; i<=lenA; i++) {
        for(int j=1;j<=lenB;j++){
            if(A[i] == B[j]){
                dp[i][j] = dp[i-1][j-1] + 1;
            }
            else dp[i][j] = max(dp[i-1][j], dp[i][j-1]);
        }
    }
    printf("%d\n",dp[lenA][lenB]);
}

int main(){
    int n;
    scanf("%d",&n);
    for (int i=0; i<n; i++) {
        //从下标为1开始读入
        lcs(gets(A+1),gets(B+1));
    }
}

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

using namespace std;
 
 
int main(){
 
  string str1;
  string str2;
  int n,s1,s2;
  int c[1001][1001] = {{}};
  int max = 0;
 
  cin >> n;
 
  for(int i = 0;i < n;i++){
 
    cin >> str1 >> str2;
 
    str1 = ' ' + str1;
    str2 = ' ' + str2;
 
 
    s1 = str1.size();
    s2 = str2.size();
 
    for(int j = 1;j < s1;j++){
      for(int k = 1;k < s2;k++){
    if(str1[j] == str2[k]){
      c[j][k] = c[j - 1][k - 1] + 1;
      if(c[j][k] > max) max = c[j][k];
    }
    else if(c[j - 1][k] > c[j][k - 1]){
      c[j][k] =  c[j - 1][k];
    }
    else {
      c[j][k] = c[j][k - 1];
    }
      }
    }
 
 
    cout << max << endl;
       
    max = 0;
 
    for(int j = 0;j <= s1;j++){
      for(int k = 0;k <= s2;k++){
        c[j][k] = 0;
      }
    }
  }
}

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

#define MAX_X 1000
#define MAX_Y 1000
using namespace std;

string X, Y;
int dp[MAX_X + 1][MAX_Y + 1] = {0};

void solve() {
    for (int i = 0; i <= X.size(); ++i) {
        for (int j = 0; j <= Y.size(); ++j) {
            if (i == 0 || j == 0)
                dp[i][j] = 0;
            else if (X[i] == Y[j])
                dp[i][j] = max(dp[i - 1][j - 1] + 1, max(dp[i][j - 1], dp[i - 1][j]));
            else
                dp[i][j] = max(dp[i][j - 1], dp[i - 1][j]);
        }
    }

    return;
}

int main() {
    int q;
    cin >> q;
    for (int i = 0; i < q; ++i) {
        cin >> X >> Y;
        solve();
        printf("%d\n", dp[X.size()][Y.size()]);
    }
}

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

int lcs(string X, string Y) {
  int cs[1001][1001];
  int m = X.size();
  int n = Y.size();
  int answer = 0;
  for (int i = 1; i <= m; i++) cs[i][0] = 0;
  for (int j = 1; j <= n; j++) cs[0][j] = 0;

  for (int i = 1; i <= m; i++) {
    for (int j = 1; j <= n; j++) {
      if (X[i - 1] == Y[j - 1]) {
        cs[i][j] = cs[i - 1][j - 1] + 1;
      } else {
        cs[i][j] = max(cs[i - 1][j], cs[i][j - 1]);
      }
      answer = max(answer, cs[i][j]);
    }
  }

  return answer;
}

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

  int n;
  cin >> n;

  string X, Y;

  for (int i = 0; i < n; i++) {
    cin >> X >> Y;
    cout << lcs(X, Y) << endl;
  }

  return 0;
}