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<bits/stdc++.h>

using namespace std;
int dp[1002][1002];
int main(){
    int T;
    cin>>T;
    while(T--){
        #ifdef LCS
        string s;
        cin>>s;
        int len=s.size();
        int *dp=new int[len+1];
        dp[0]=1;
        int ans=1;
        for(int i=1;i<len;i++){
            char ch=s[i];
            int cnt=0;
            for(int j=0;j<=i-1;j++){
                if(s[j]<ch) cnt=max(cnt,dp[j]);
            }
            dp[i]=cnt+1;
            ans=max(ans,dp[i]);
        }
        cout<<ans<<endl;
        #endif//LCS
        string s1,s2;
        cin>>s1>>s2;
        int len1=s1.size(),len2=s2.size();
        int len=max(len1,len2);
        for(int i=0;i<=len;i++) {
            dp[0][i]=0;
            dp[i][0]=0;
        }
        int ans=0;
        for(int i=0;i<len1;i++){
            for(int j=0;j<len2;j++){
                if(s1[i]==s2[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[len1][len2]<<endl;
    }
}

C++: #include <bits/stdc++.h>
#define LOOP(n) for (int _i = 0; _i < (n); _i++)
#define REP(i, n) for (int i = 0; i < (n); ++i)
#define RREP(i, n) for (int i = (n); i >= 0; --i)
#define FOR(i, r, n) for (int i = (r); i < (n); ++i)
#define ALL(obj) begin(obj), end(obj)
using namespace std;
using ll = long long;
using ull = unsigned long long;
using P = pair<int, int>;
using Graph = vector<vector<int>>;

const int INF = 2100100100;
const int MOD = 1e9 + 7;

// 多次元 vector 生成
template <class T>
vector<T> make_vec(size_t a) {
    return vector<T>(a);
}
template <class T, class... Ts>
auto make_vec(size_t a, Ts... ts) {
    return vector<decltype(make_vec<T>(ts...))>(a, make_vec<T>(ts...));
}
template <class T>
bool chmax(T &a, const T &b) {
    if (a < b) {
        a = b;
        return 1;
    }
    return 0;
}
template <class T>
bool chmin(T &a, const T &b) {
    if (b < a) {
        a = b;
        return 1;
    }
    return 0;
}

int N, M, K, Q, W, H, R, C;
int dp[1100][1100];

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

    cin >> Q;
    vector<int> ans;

    REP(i, Q) {
        string a, b;
        cin >> a >> b;
        memset(dp, 0, sizeof(dp));

        FOR(i, 1, (int)a.size() + 1) {
            FOR(j, 1, (int)b.size() + 1) {
                if (a[i - 1] == b[j - 1]) chmax(dp[i][j], dp[i - 1][j - 1] + 1);
                chmax(dp[i][j], dp[i - 1][j]);
                chmax(dp[i][j], dp[i][j - 1]);
            }
        }
        /*
        REP(i, (int)a.size() + 1) {
            REP(j, (int)b.size() + 1) { cout << dp[i][j] << " "; }
            cout << endl;
        }
        */
        ans.push_back(dp[(int)a.size()][(int)b.size()]);
    }

    for (auto i : ans) {
        cout << i << endl;
    }

    return 0;
}

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

using namespace std;

int lcslen[1001][1001];
int compute_lcslen(const string &x,const string &y);

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

  return 0;
}

int compute_lcslen(const string &x,const string &y){
  for(int i=1;i<=x.length();++i){
    for(int j=1;j<=y.length();++j){
      if(x[i]==y[j]){
        lcslen[i][j] = lcslen[i-1][j-1]+1;
      }else{
        lcslen[i][j] = max(lcslen[i-1][j],lcslen[i][j-1]);
      }
    }
  }
  return lcslen[x.length()][y.length()];
}

C++: #include <iostream>
#include <string>
#include <algorithm>
#define MAX 1000

using namespace std;

string s,t;
int dp[MAX + 1][MAX + 1];

int LCS(void){

  for( int i = 0 ; i < s.size() ; i++ ){
    for( int j = 0 ; j < t.size() ; 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]);
      }
    }
  }
  return dp[s.size()][t.size()];
}


int main(void){

  int n;
  cin >> n;
  while(n--){

    memset(dp, 0 , sizeof(dp) );

    cin >> s >> t;
    cout << LCS() << endl;

  }
  return 0;
}

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

int LCS(string s, string t);

int main(void){
  int n;
  string s;
  string t;
  cin>>n;
  for(int i=0;i<n;i++){
    cin>>s;
    cin>>t;
    cout<<LCS(s,t)<<endl;
  }
}

int LCS(string s, string t){
  int a[s.length()+1][t.length()+1];
  for(int i=0;i<s.length()+1;i++){
    for(int j=0;j<t.length()+1;j++){
      a[i][j]=0;
    }
  }
  char S,T;
  for(int i=1;i<s.length()+1;i++){
    for(int j=1;j<t.length()+1;j++){
      S=s[i-1];
      T=t[j-1];
      if(S!=T){
        a[i][j]=max({a[i-1][j-1],a[i-1][j],a[i][j-1]});
      }
      else{
        a[i][j]=max({a[i-1][j-1]+1,a[i-1][j],a[i][j-1]});
      }
    }
  }
  return a[s.length()][t.length()];
}