Go: package main

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

var (
	nstr   func() string
	stdout *bufio.Writer
)

func init() {
	nstr = newReadString(os.Stdin)
	stdout = bufio.NewWriter(os.Stdout)
}

func main() {
	defer stdout.Flush()

	n := nint()
	xList := make([]string, n)
	yList := make([]string, n)

	for i:=0;i<n ;i++  {
		xList[i] = nstr()
		yList[i] = nstr()
	}

	for i := 0; i<n	; i++  {
		fmt.Println(lcs(xList[i], yList[i]))
	}

}

func lcs(x string, y string) int{
	var m = len(x)
	var n = len(y)

	c := make([][]int, m+1)
	for i:= range c{
		c[i] = make([]int, n+1)
	}
	for i:=	1;i<=m ;i++  {
		for j:=1;j<=n ;j++  {
			if x[i-1] == y[j-1]{
				c[i][j] = c[i-1][j-1] + 1
			}else{
				c[i][j] = int(math.Max(float64(c[i-1][j]), float64(c[i][j-1])))
			}


		}
	}
	return c[m][n]

}


func newReadString(ior io.Reader) func() string {
	r := bufio.NewScanner(ior)
	r.Buffer(make([]byte, 1024), int(1e+11))
	r.Split(bufio.ScanWords)

	return func() string {
		if !r.Scan() {
			panic("Scan failed")
		}
		return r.Text()
	}
}

func nint64() int64 {
	i, err := strconv.ParseInt(nstr(), 0, 64)
	if err != nil {
		panic(err.Error())
	}
	return i
}

func nint() int {
	return int(nint64())
}

func getIntSlice(n int) []int {
	b := make([]int, n)
	for i := 0; i < n; i++ {
		b[i] = nint()
	}
	return b
}

func getStringSlice(n int) []string {
	b := make([]string, n)
	for i := 0; i < n; i++ {
		b[i] = nstr()
	}
	return b
}

func gcd(x, y int) int {
	if y == 0 {
		return x
	}
	return gcd(y, x%y)
}

func lcm(x, y int) int {
	return x * y / gcd(x, y)
}

func contains(s []int, e int) bool {
	for _, a := range s {
		if a == e {
			return true
		}
	}
	return false
}

func bin(i int, prefix bool) string {
	i64 := int64(i)

	if prefix {
		return "0b" + strconv.FormatInt(i64, 2)
	} else {
		return strconv.FormatInt(i64, 2)
	}
}

func strReverse(s string) string {
	runes := []rune(s)
	for i, j := 0, len(runes)-1; i < j; i, j = i+1, j-1 {
		runes[i], runes[j] = runes[j], runes[i]
	}

	return string(runes)
}

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

int lcs(string str1, string str2) {
	int n1 = str1.size();
	int n2 = str2.size();
	int A[n1 + 1][n2 + 1];
	for (int i = 0; i < n1; i++) A[i][0] = 0;
	for (int j = 0; j < n1; j++) A[0][j] = 0;

	for (int i = 1; i <= n1; i++) {
		for (int j = 1; j <= n2; j++) { 
			if (str1[i - 1] == str2[j - 1]) {
				A[i][j] = A[i - 1][j - 1] + 1; //?????´??????+1????????¨???????????¨???????????\??????i-1, j-1????????´??°???i,j?????????????????????+1????????¨???????????¨i-1,j??¨?????§?????????????????¶??????
			} else {
				A[i][j] = max(A[i - 1][j], A[i][j - 1]); //?????´?????????????????§i,j??????????????? i-1,j??¨i,j-1
			}
		}
	}
	return A[n1][n2];
}

int main() {
	int n;
	string str1, str2;
	cin >> n;
	for (int i = 0; i < n; i++) {
		cin >> str1 >> str2;
		cout << lcs(str1, str2) << endl;
	}
	return 0;
}

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

static const int N = 1000;

int lcs(string X,string Y){
    int c[N+1][N+1];    //c[i][k]???Xi??¨Yk???LCS??¨??????????????????
    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 k=1;k<=n;k++) c[0][k] = 0;
    c[0][0] = 0;

    for(int i=1;i<=m;i++){
        for(int k=1;k<=n;k++){
            if(X[i]==Y[k]){
                c[i][k] = c[i-1][k-1] + 1;
            } else {
                c[i][k] = max(c[i-1][k],c[i][k-1]);
            }
            maxl = max(maxl,c[i][k]);
        }
    }

    return maxl;
}

int main(){
    
}

C++: #include <iostream>
#include <fstream>
#include <stdio.h>
#include <algorithm>
#include <string>

#define MAX 10000

using namespace std;

int n;
int LCS[MAX][MAX];

void solve(string a, string b){
    int m = a.size();
    int n = b.size();
    int maxl = 0;
    for(int i=0; i<m; i++){
        for(int j=0; j<n; j++){
            LCS[i][j] = 0;
        }
    }
    bool tmp_ok = false;
    for(int i=0; i<n; i++){
        if(a[0] == b[i] || tmp_ok){
            LCS[i][0] = 1;
            maxl = 1;
            tmp_ok = true;
        }
    }
    tmp_ok = false;
    for(int i=0; i<m; i++){
        if(a[i] == b[0] || tmp_ok){
            LCS[0][i] = 1;
            maxl = 1;
            tmp_ok = true;
        }
    }
    for(int i=1; i<n; i++){
        for(int j=1; j<m; j++){
            if(a[j] == b[i]){
                LCS[i][j] = LCS[i-1][j-1]+1;
            }
            else if(LCS[i-1][j]>=LCS[i][j-1]){
                LCS[i][j] = LCS[i-1][j];
            }
            else LCS[i][j] = LCS[i][j-1];
            maxl = max(maxl, LCS[i][j]);
        }
    }
    
    cout << maxl << endl;
}

int main(int argc, const char * argv[]) {
    // input from txt
    
    /////////
    //write//
    /////////
    
    cin >> n;
    for(int i=0; i<n; i++){
        string str_a;
        string str_b;
        cin >> str_a >> str_b;
        solve(str_a, str_b);
    }
    
    return 0;
}

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

int main(){
  int n;
  char x[1000],y[1000];
  int dp[1001][1001];
  //load n;
  cin >>n;
  for(int i=0;i<n;i++){
    scanf("%s",x);
    scanf("%s",y);
    for(int j=0;j<strlen(x);j++){
      for(int k=0;k<strlen(y);k++){
	if(x[j]==y[k]){
	  dp[j+1][k+1]=dp[j][k]+1;
	}

	else{
	  if(dp[j][k+1]>dp[j+1][k]){
	    dp[j+1][k+1]=dp[j][k+1];
	  }

	  else{
	    dp[j+1][k+1]=dp[j+1][k+1];
	  }


	}
      }
    }

  }
  cout <<dp[strlen(x)][strlen(y)]<<endl;

  return 0;
}

C++: #include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
int n, xl, yl, dp[1003][1003]; char x[1003], y[1003];
int main() {
	scanf("%d", &n);
	for(int i = 0; i < n; i++) {
		scanf("%s", x); xl = strlen(x);
		scanf("%s", y); yl = strlen(y);
		memset(dp, 0, sizeof(dp));
		for(int i = 1; i <= xl; i++) {
			for(int j = 1; j <= yl; j++) {
				if(x[i - 1] == y[i - 1]) 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[xl][yl]);
	}
}

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

int lengthOfLcs_r(const char x[], const char y[], int ix, int iy, int xsize, int ysize) {
	if (ix == xsize || iy == ysize) {
		return 0;
	}
	if (x[ix] == y[iy]) {
		return lengthOfLcs_r(x, y, ix + 1, iy + 1, xsize, ysize) + 1;
	}
	return max(lengthOfLcs_r(x, y, ix, iy + 1, xsize, ysize), lengthOfLcs_r(x, y, ix + 1, iy, xsize, ysize));
}

int lengthOfLcs(string x, string y) {
	return lengthOfLcs_r(x.c_str(), y.c_str(), 0, 0, x.length(), y.length());
}

int main() {
	int q;
	string x, y;

	cin >> q;
	for (int i = 0; i < q; ++i) {
		cin >> x >> y;
		cout << lengthOfLcs(x, y) << endl;
	}
	return 0;
}

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

void fnInput(vector<string>& rvsStrX, vector<string>& rvsStrY)
{
  int nMaxSiz;
  cin >> nMaxSiz;
  rvsStrX.resize(nMaxSiz);
  rvsStrY.resize(nMaxSiz);

  for (int i = 0; i < nMaxSiz; ++i)
  {
    cin >> rvsStrX[i] >> rvsStrY[i];
    rvsStrX[i] = ' ' + rvsStrX[i];
    rvsStrY[i] = ' ' + rvsStrY[i];
  }
}

int fnLngCmnSubseq(const vector<string>& cnrvsStrX, const vector<string>& cnrvsStrY)
{
  for (int i = 0; i < cnrvsStrX.size(); ++i)
  {
    const int nMAXNX = cnrvsStrX[i].size();
    const int nMAXNY = cnrvsStrY[i].size();
    vector<vector<int>> vvnLcsDP(nMAXNX, vector<int>(nMAXNY, 0));

    for (int nx = 1; nx < nMAXNX; ++nx)
      for (int ny = 1; ny < nMAXNY; ++ny)
        if (cnrvsStrX[i][nx] == cnrvsStrY[i][ny])
          vvnLcsDP[nx][ny] = vvnLcsDP[nx - 1][ny - 1] + 1;
        else
          vvnLcsDP[nx][ny] = max(vvnLcsDP[nx - 1][ny], vvnLcsDP[nx][ny - 1]);

    cout << vvnLcsDP[nMAXNX - 1][nMAXNY - 1] << endl;
  }
}

int main()
{
  cin.tie(0);
  ios::sync_with_stdio(false);
  vector<string> vsStrX, vsStrY;

  fnInput(vsStrX, vsStrY);
  fnLngCmnSubseq(vsStrX, vsStrY);
  return 0;
}