Go: package main

import (
	"fmt"
	"os"
	"strconv"
	"bufio"
	"strings"
	"sort"
)

// define
var (
	sc = bufio.NewScanner(os.Stdin)
)

func bordersInt(in_map [][]int, invalid int) [][]int{
	H, W := len(in_map), len(in_map[0])
	out_map := make([][]int, H+2)
	for h:=0; h<H+2; h++ {
		out_map[h] = make([]int, W+2)
		for w:=0; w<W+2; w++ {
			out_map[h][w] = invalid
		}
	}
	for h:=0; h<H; h++{
		for w:=0; w<W; w++{
			out_map[h+1][w+1] = in_map[h][w] 
		}
	}
	return out_map
}

func bordersString(in_map [][]string, invalid string) [][]string{
	H, W := len(in_map), len(in_map[0])
	out_map := make([][]string, H+2)
	for h:=0; h<H+2; h++ {
		out_map[h] = make([]string, W+2)
		for w:=0; w<W+2; w++ {
			out_map[h][w] = invalid
		}
	}
	for h:=0; h<H; h++{
		for w:=0; w<W; w++{
			out_map[h+1][w+1] = in_map[h][w] 
		}
	}
	return out_map
}

func scanIntLine(len int) []int{
	arr := make([]int, len)
	for i:=0; i<len; i++{
		sc.Scan()
		tmp, err := strconv.Atoi(sc.Text())
		if err == nil{
			arr[i] = tmp
		}
	}
	return arr
}

func scanStringLine(len int) []string{
	arr := make([]string, len)
	for i:=0; i<len; i++{
		sc.Scan()
		arr[i] = sc.Text()
	}
	return arr
}

func scanIntSplit(len int) []int{
	arr := make([]int, len)
	sc.Scan()
	for i, v := range strings.Split(sc.Text(), " "){
		tmp, err := strconv.Atoi(v)
		if err == nil{
			arr[i] = tmp
		}
	}
	return arr
}

func maxInt(args... int) int{
	sort.Ints(args)
	return args[len(args)-1]
}

func main(){
	buf := make([]byte, 0)
    sc.Buffer(buf, 1000000009)
	var n int 
	fmt.Scan(&n)
	dp := make([][]int, 1003)
	for i:=0; i<1003; i++ {
		dp[i] = make([]int, 1003)
	}
	input_lines := scanStringLine(2*n)
	for i:=0; i<n; i++ {
		S, T := input_lines[2*i], input_lines[2*i+1]
		lenS, lenT := len(S), len(T)
		for i:=1; i<lenS+1; i++ {
			for j:=1; j<lenT+1; j++ {
				if S[i-1] == T[j-1] {
					dp[i][j] = maxInt(dp[i-1][j-1]+1, dp[i-1][j], dp[i][j-1])
				} else {
					dp[i][j] = maxInt(dp[i-1][j], dp[i][j-1])
				}
			}
		}
		fmt.Println(dp[lenS][lenT])
	}
}

C++: #include <iostream>
#include <vector>
#include <string>
#include <stack>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <algorithm>	// require sort next_permutation count __gcd reverse etc.
#include <cstdlib>	// require abs exit atof atoi 
#include <cstdio>		// require scanf printf
#include <functional>
#include <numeric>	// require accumulate
#include <cmath>		// require fabs
#include <climits>
#include <limits>
#include <cfloat>
#include <iomanip>	// require setw
#include <sstream>	// require stringstream 
#include <cstring>	// require memset
#include <cctype>		// require tolower, toupper
#include <fstream>	// require freopen
#include <ctime>		// require srand
#define rep(i,n) for(int i=0;i<(n);i++)
#define ALL(A) A.begin(), A.end()

using namespace std;

typedef long long ll;
typedef pair<int, int> P;

int dp[1005][1005];

int main()
{
	ios_base::sync_with_stdio(0);
	int n; cin >> n;
	while (n-- ){
		memset (dp, 0, sizeof (dp ) );
		string s, t;
		cin >> s >> t;
		int n = s.length();
		int m = t.length();
		rep (j, m ) if (s[0] == t[j] ) dp[0][j] = 1;
		rep (i, n ) if (s[i] == t[0] ) dp[i][0] = 1;

		for (int i = 1; i < n; i++ ){
			for (int j = 1; j < m; j++ ){
				dp[i][j] = max (dp[i][j], dp[i-1][j-1] + (s[i] == t[j] ? 1 : 0 ) );
				dp[i][j] = max (dp[i][j], dp[i-1][j] );
				dp[i][j] = max (dp[i][j], dp[i][j-1] );
			} // end for
		} // end for
/*
		rep (i, n ){
			rep (j, m ){
				printf ("%3d", dp[i][j] );
			} // end rep
			printf ("\n" );
		} // end rep
*/		
		int res = dp[n-1][m-1]; 		
		cout << res << endl;
	} // end loop

//	printf ("%d\n", res );
		
	return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define FOR(i,a,b) for(int i=a;i<=b;i++)
#define FORD(i,a,b) for(int i=a;i>=b;i--)
#define ALL(a)  (a).begin(),(a).end()
#define SZ(a) int((a).size())
#define SORT(c) sort((c).begin(),(c).end())
#define MEMSET(v, h) memset((v), h, sizeof(v))
#define sqr(x) ((x) * (x))
#define bit(n) (1LL<<(n))
#define pcnt(x) __builtin_popcountll(x)
#define PB push_back
#define MP make_pair
#define endl "\n"
using Edge = pair<int,int>;
using Graph = vector<vector<Edge>>;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
// ll gcd(ll a,ll b){return b?gcd(b,a%b):a;}
// ll lcm(ll a,ll b){return a/gcd(a,b)*b;}



int main() {
  int q; cin >> q;
  FOR(i,0,q-1){
    int dp[1010][1010];
    string a,b; cin >> a >> b;
    MEMSET(dp,0);
    FOR(j,1,a.length()){
      FOR(k,1,b.length()){
        if(a[j-1] == b[k-1]) dp[j][k] = dp[j-1][k-1] + 1;
        else dp[j][k] = max(dp[j-1][k],dp[j][k-1]);
      }
    }
    // FOR(i,1,a.length()){
    //   FOR(j,1,b.length()){
    //     cout << dp[i][j] << " ";
    //   }
    //   cout << "\n";
    // }
    cout << dp[a.length()][b.length()] << "\n";
  }
}

C++: #include <iostream>

using namespace std;

/**
 *  lcs(m,n) = 
 *  if x[m] == y[n] lcs[m-1,n-1]+1
 *  max(lcs[m-1,n],lcs[m,n-1])
 *
 */

string x, y;

int lcs(int m, int n)
{
	if (m == -1 || n== -1) return 0;
	if (x[m] == x[n]) return lcs(m-1,n-1) + 1;
	int xx = lcs(m-1,n);
	int yy = lcs(m,n-1);
	return xx > yy ? xx : yy;
}

int main()
{
	int n = 0;
	x.resize(150);
	y.resize(150);
	cin >> n; 
	for (int i=0;i<n;i++)
	{
		cin >> x;
		cin >> y;
		return lcs(x.size()-1, y.size()-1);
	}
}

C++: #include<stdio.h>
#include<string.h>
 
char X[1001],Y[1001];
 
int LCS_Length(void){
  int i,j;
  int m = strlen(X);
  int n = strlen(Y);
  int c[m+1][n+1];
 
  for(i=1 ; i<=m ; i++) c[i][0] = 0;
  for(j=0 ; j<=n ; j++) c[0][j] = 0;
   
  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 if(c[i-1][j] >= c[i][j-1]) c[i][j] = c[i-1][j];
      else c[i][j] = c[i][j-1];
    }
  }
  return c[m][n]; 
}
 
main(){
  int i,n;
  scanf("%d",&n);
  for(i=0 ; i<n ; i++){
    scanf("%s%s",X,Y);
    printf("%d\n",LCS_Length());
  }
  return 0;
}

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

using namespace std;
static const int N = 100;
static const int INFTY = (1<<21);

int n, M[N][N];
int d[N];

void bfs(int s) {
    queue<int> q;
    q.push(s);
    for(int i = 0; i < n; i++) d[i] = INFTY;
    d[s] = 0;
    int u;
    while( !q.empty() ) {
        u = q.front(); q.pop();
        for (int v = 0; v < n; v++) {
            if( M[u][v] == 0 || d[v]!= INFTY ) continue;
            d[v] = d[u] + 1;
            q.push(v);
        }
    }
    for (int i = 0; i < n; i++) {
        cout << i+1 << " " << (d[i] == INFTY ? (-1) : d[i]) << endl;
    }
}

int main() {
    int u, k, v;

    cin >> n;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            M[i][j] = 0;
        }
    }

    for(int i = 0; i < n; i++) {
        cin >> u >> k;
        u--;
        for (int j = 0; j < k; j++) {
            cin >> v;
            v--;
            M[u][v] = 1;
        }
    }

    bfs(0);

    return 0;
}

C++: #include<stdio.h>
#include<string.h>
    
int LCS(char *X, char *Y){
  int i,j,m,n,c[1001][1001];
  m = strlen(X);
  n = strlen(Y);
      
  for(i=0; i<m; i++){
    c[i][0] = 0;
  }
  for(j=0; j<n; j++){
    c[0][j] = 0;
  }
    
  for(i=1;i<m+1;i++){
    for(j=1;j<n+1;j++){
      if (X[i-1]==Y[j-1]) 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];
    }
  }
  return c[i-1][j-1];
}
    
int main(){
  int i, q;
  char X[1001], Y[1001];
      
  scanf("%d", &q);
  for(i=0; i<q; i++){
    scanf("%s", X);
    scanf("%s", Y);
    printf("%d\n", LCS(X, Y));
    
  }
  return 0;
}