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 <cstdio>
#include <cstdlib>
#include <cassert>
#include <string>
#include <cstring>
#include <vector>
#include <list>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <algorithm>

using namespace std;

// ---------------------
// repetition
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)

// debug
#define dump(x)  cerr << #x << " = " << (x) << endl;
#define debug(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << endl;

// ---------------------
#define INF 922337203685477580
typedef long long ll;

int dp[1000][1000];

int main() {
  int q;
  cin >> q;
  REP(loop, q) {
    char S[1000], T[1000];
    cin >> S >> T;

    FOR(i, strlen(S)) {
      FOR(j, strlen(T)) {
        dp[i][j] = 0;
      }
    }
    for (int i = 0; i < strlen(S); i++) {
      for (int j = 0; j < strlen(T); j++) {
        if (S[i] == T[j]) {
          dp[i + 1][j + 1] = dp[i][j] + 1;
        } else {
          dp[i + 1][j + 1] = max(dp[i + 1][j], dp[i][j + 1]);
        }
      }
    }
    cout << dp[strlen(S) - 1][strlen(T) - 1] << endl;
  }

  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
int C[1000][1000];
int lc(string F, string S){
    fill(C[0],C[1000],0);
    int m = F.size(), n = S.size();
    int len=0;
    for(int i=0; i<m; i++){
        for (int j = 0; j < n; ++j) {
            if (F[i] == S[j]) {
                if (i - 1 >= 0 && j - 1 >= 0)
                    C[i][j] = C[i - 1][j - 1] + 1;
                else
                    C[i][j] = 1;
            } else if (i - 1 >= 0 && j - 1 >= 0) {
                C[i][j] = max(C[i-1][j], C[i][j - 1]);
            }
            len = max(len, C[i][j]);
        }
    }
    return len;
}

int main() {
    ios::sync_with_stdio(false);
    int n;
    cin >> n;
    string ar[n*2];
    for (int i = 0; i < n * 2; ++i) {
        cin >> ar[i];
    }
    for (int j = 0; j < n*2; j+=2) {
        cout << lc(ar[j],ar[j+1]) << endl;
    }
    return 0;
}

C++: // Ref : https://book.mynavi.jp/ec/products/detail/id=35408

#include <iostream>
#include <algorithm>
#include <limits.h>
using namespace std;

static const int N = 100;;

int main() {
	int n; cin >> n;
	int p[N + 1], m[N + 1][N + 1]; // m_ij is partial LCS between i to j.
	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++) { // l is a length of partial LCS.
		for (int i = 1; i <= n - l + 1; i++) {
			int j = i + l - 1;
			m[i][j] = INT_MAX;
			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[j] * p[k]);
			}
		}
	}
	cout << m[1][n] << endl;

	return 0;
}

C++: #define _CRT_SECURE_NO_WARNINGS
#define _USE_MATH_DEFINES
#include <iostream>
#include <cstdlib>
#include <string>
#include <cstdio>
#include <algorithm>
#include <cmath>
#include <vector>
#include <set>
#include <random>
#include <map>

using namespace std;

int LCS[1010][1010] = {};

int LCSLength(string strX,string strY) {

    int strXSize = strX.length();
    int strYSize = strY.length();
    for (int i = 0; i < strXSize + 1; i++) {
	for (int j = 0; j < strYSize + 1; j++) {
	    if (i == 0 || j == 0) {
		LCS[i][j] = 0;
	    }
	}
    }

    for (int i = 1; i < strXSize + 1; i++) {
	for (int j = 1; j < strYSize + 1; j++) {

	    //LCS[i]==LCS[j]
	    if (strX[i - 1] == strY[j - 1]) {
		LCS[i][j] = LCS[i - 1][j - 1] + 1;
	    }
	    else {
		LCS[i][j] = max(LCS[i][j - 1], LCS[i - 1][j]);
	    }
	}
    }

    return LCS[strXSize][strYSize];
}

int main() {

    //cin.tie(0);
    //ios::sync_with_stdio(false);

    int q; scanf("%d", &q);

    string strX;
    string strY;
    while (q-- > 0) {
	cin >> strX;
	cin >> strY;
	printf("%d\n", LCSLength(strX, strY));
    }



    return 0;

}

C++: #include<iostream>
#include<string>
int main()
{
  int n;
  int an[1000];
  int l=0;
  std::cin>>n;
  std::string x;
  std::string y;
  int ans[1001][1001];
  int j,k;
  for(int i=0;i<n;i++){
    std::cin>>x;
    std::cin>>y;
    for(int j=0;j<=1000;j++){
      for(int k=0;k<=1000;k++){
	ans[j][k]=0;
      }
    }
    for(int j=1;j<=x.size();j++){
      for(int k=1;k<=y.size();k++){
	if(x[j]==y[k]){
	  ans[j][k]=ans[j-1][k-1]+1;
	}else{
	  if(ans[j][k-1]>ans[j-1][k]){
	    ans[j][k]=ans[j][k-1];
	  }else{
	    ans[j][k]=ans[j-1][k];
	  }
	}
      }
    }
    std::cout<<ans[x.size()-1][y.size()-1]<<'\n';  
  }
  return 0;
}

C++: #include <bits/stdc++.h>
#define FOR(i, a, b) for (int i = (a), i##_max = (b); i < i##_max; ++i)
#define RFOR(i, a, b) for (int i = (b)-1, i##_min = (a); i >= i##_min; --i)
#define REP(i, n) for (int i = 0, i##_len = (n); i < i##_len; ++i)
#define RREP(i, n) for (int i = (n)-1; i >= 0; --i)
#define ALL(obj) (obj).begin(), (obj).end()

using namespace std;
using vi = vector<int>;
using vd = vector<double>;
using i64 = int64_t;

constexpr int INF = 1 << 30;
constexpr int MOD = 1000000007;

template <typename T>
void print(vector<T> &v) {
  REP(i, v.size()) {
    if (i) cout << " ";
    cout << v[i];
  }
  cout << endl;
}

int main() {
  int n;
  cin >> n;
  string x, y;
  REP(i, n) {
    cin >> x >> y;
    auto xs = x.size();
    auto ys = y.size();
    x = ' ' + x;
    y = ' ' + y;
    vector<vi> dp(xs + 1, vi(ys + 1, 0));
    FOR(xi, 1, xs + 1) {
      FOR(yi, 1, ys + 1) {
        if (x[xi] == y[yi])
          dp[xi][yi] = dp[xi - 1][yi - 1] + 1;
        else
          dp[xi][yi] = max(dp[xi - 1][yi], dp[xi][yi - 1]);
      }
    }
    cout << dp[xs][ys] << endl;
  }
}