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

int dp[1001][1001];
int main() {
	int b;
	scanf("%d", &b);
	char e[1001];
	char f[1001];
	for (int c = 0; c < b; c++) {
		scanf("%s%s", e, f);
		for (int g = 0; g <= strlen(e); g++) {
			for (int h = 0; h <= strlen(f); h++) {
				dp[g][h] = 0;
			}
		}
		for (int g = 0; g < strlen(e); g++) {
			for (int h = 0; h < strlen(f); h++) {
				if (e[g] == f[h]) {
					dp[g+1][h+1] = dp[g][h] + 1;
				}
				else {
					if (dp[g][h + 1] > dp[g + 1][h])dp[g + 1][h + 1] = dp[g][h + 1];
					else dp[g + 1][h + 1] = dp[g+1][h];
				}
			}
		}
		printf("%d\n", dp[strlen(e)][strlen(f)]);
	}
}

C++: #include<cstdio>
#include<iostream>
#include<algorithm>
#include<string>
#include<queue>
#include<vector>
#include<functional>
#include<cmath>
#include<map>
#include<stack>
#include<set>
#include<numeric>
#include<limits>
#include<iterator>

#define all(x) (x).begin(),(x).end()
#define rall(x) (x).rbegin(),(x).rend()
#define rep(i,n) for(int i=0; i<n; i++)
#define INF (1<<20)

using namespace std;
typedef long long ll;
typedef pair<int, int> pi;
typedef pair<ll, ll> pl;
typedef pair<ll, char> plc;

int L[1010][1010];

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

	for (int i = 0; i < n; i++) {
		L[0][0] = L[0][1] = L[1][0] = 0;
		string s1, s2;
		cin >> s1 >> s2;

		for (int j = 1; j <= s1.size(); j++) {
			for (int k = 1; k <= s2.size(); k++) {
				if (s1[j - 1] == s2[k - 1]) {
					L[j][k] = L[j - 1][k - 1] + 1;
				}
				else {
					L[j][k] = max(L[j-1][k],L[j][k-1]);
				}
			}
		}
		cout << L[s1.size()][s2.size()] << endl;
	}
	return	0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define For(I,A,B) for(int I=(A); I < (B); ++I)
int c[1005][1005];
int main()
{
int t;
string p;
cin>>t;
getline(cin,p);
while(t--){

int x,y,z,k=0,l,i,j;
string a,b;

 For(i,0,1005)
 For(j,0,1005)
 c[i][j]=0;

 getline(cin,a);
 getline(cin,b);
 x=a.length();
 y=b.length();

 For(i,1,x+1)
 For(j,1,y+1)
 {
     if(a[i-1]==b[j-1]) c[i][j]=c[i-1][j-1]+1;
     else  c[i][j]=max(c[i-1][j],c[i][j-1]);
 }
    cout<<c[x][y]<<endl;

}

    return 0;
}

C++: #include <iostream>
using namespace std;
#define MAX 2000

int c[MAX][MAX];
void lcs(string x, string y)
{
    int m = x.size();
    int n = y.size();
    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 if(c[i-1][j]>=c[i][j-1])
                c[i][j] = c[i-1][j];
            else
                c[i][j] = c[i][j-1];
        }
    }
}
int main()
{
    int n;
    string s1, s2;
    cin >> n;
    while(n--)
    {
        cin >> s1 >> s2;
        lcs(s1,s2);
        cout << c[s1.size()][s2.size()] << endl;
    }
    return 0;
}

C++: /*
 * Problem Description: Longest Common Subsequence
 * Category: Dynamic Programming
 * Author: Khan
 * Date: 18th October, 2017
 */

#include <iostream>
#include <string>
#include <algorithm>

using namespace std;

static const int N = 10000;

int lcs(string x, string y)
{
    int c[N + 1][N + 1];
    int m = x.size();
    int n = y.size();
    int maxLength = 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]);
            maxLength = max(maxLength, c[i][j]);
        }
    }
    return maxLength;
}

int main(int argc, char const *argv[])
{
    //freopen("sample.txt", "r", stdin);
    string x, y;
    int n;
    cin >> n;
    for (int i = 0; i < n; ++i)
    {
        cin >> x >> y;
        cout << lcs(x, y) << endl;
    }
    return 0;
}

C++: #include <limits.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <algorithm>
#include <cassert>
#include <cfloat>
#include <complex>
#include <functional>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <vector>

using namespace std;

#define chmax(x, y) x = max(x, y)
#define chmin(x, y) x = min(x, y)
#define rep(i, n) for (ll i = 0; i < (n); ++i)
#define Sort(v) sort(v.begin(), v.end())
#define Reverse(v) reverse(v.begin(), v.end())
#define Lower_bound(v, x) \
  distance(v.begin(), lower_bound(v.begin(), v.end(), x))
#define Upper_bound(v, x) \
  distance(v.begin(), upper_bound(v.begin(), v.end(), x))

using ll = long long;
using ull = unsigned long long;
using P = pair<ll, ll>;
using T = tuple<ll, ll, ll>;
using vll = vector<ll>;
using vP = vector<P>;
using vT = vector<T>;
using vvll = vector<vector<ll>>;
using vvP = vector<vector<P>>;
using dqll = deque<ll>;

ll dx[9] = {-1, 1, 0, 0, -1, -1, 1, 1, 0};
ll dy[9] = {0, 0, -1, 1, -1, 1, -1, 1, 0};

const ll INF = 1LL << 50;

const ll mod = 1e9 + 7;

int main() {
  ll q;
  cin >> q;
  rep(i_q, q) {
    string s, t;
    cin >> s >> t;
    ll ns = (ll)s.size(), nt = (ll)t.size();
    vvll dp(ns + 1, vll(nt + 1, 0));
    rep(i, ns) rep(j, nt) {
      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]);
      }
    } // j, i
    cout << dp[ns][nt] << endl;
  }  // q

  return 0;
}