I would also appreciate it if somebody were to explain to me the solution to this problem because I think my logic is incorrect.
public class FibanacciSequence {
public static void main(String[] args)
{
fibSeq(5,5);
}
public static int[] fibSeq(int startNum, int iterations)
{
int[] arr = new int[iterations];
int nextNum = 0;
arr[0] = startNum;
if(iterations == 0)
{
return arr;
}
else
{
arr[nextNum] = startNum+startNum;
arr[nextNum+1] = nextNum + startNum;
arr=fibSeq(nextNum,iterations-1);
}
return arr;
}
}
When iterations <= 0, your code will fail on the line
arr[0] = startNum;
When 0 < iterations <= nextNum + 1, your code will fail on the lines
arr[nextNum] = startNum + startNum;
arr[nextNum + 1] = nextNum + startNum;
You should probably work out your plan in more detail on paper before coding.
struct googlePlayApp{
string name;
string category;
double rating;
int reviews;
googlePlayApp *next;
};
void appInsert(googlePlayApp &newApp, int &cmps) {
int slot = hash1(newApp.name, HASH_SIZE);
int cmps1 = 1;
googlePlayApp *tmp = appHash[slot];
if (tmp == 0)
appHash[slot] = &newApp;
else
{
while(tmp->next != 0)
{
tmp = tmp->next;
cmps1++;
}
tmp->next = &newApp;
}
cmps += cmps1;
}
while (getline(inFile, inputLine)) {
googlePlayApp newApp;
readSingleApp(inputLine, newApp);
appInsert(newApp, cmps);
linesRead++;
}
My program stops on the 65th iteration of the while loop....
64th for the appInsert call...
Why can't I get this to work?
This is a program where it reads a data file and stores it in a hash table and collision dealt with open addressing....
updated question
bool appFind(const string &name, googlePlayApp &foundApp, int &cmps) {
// Implement this function
int slot = hash1(name);
int cmps1 = 1;
googlePlayApp *tmp = appHash[slot];
while(tmp && tmp->name != name)
{
cmps1++;
tmp = tmp->next;
}
cmps += cmps1;
if(tmp)
{
foundApp.name = appHash[slot]->name;
foundApp.category = appHash[slot]->category;
foundApp.rating = appHash[slot]->rating;
foundApp.reviews = appHash[slot]->reviews;
}
else return false;
}
this is my serach function and I'm trying to search if an app exists based on the data I stored from my code above. I'm trying to search it by the hash addresses, but it's not working...
I'm trying to create a new list from findall or where and modify that new list without it making changes to the original. When creating list2 from FindAll and a change is made to list2, it should not affect list1. How come?
Edit... Used combination of both answers which seems to be working. Any foreseen issues??? Working code edited
Edit... It's not working. A class that is a property of the object does not have its data copied... Any ideas??? I can't see why just copy or clone isn't plain and simple for a list.
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Started");
List<SampleData> list1 = SampleData.MakeList(3);
for (int i = 0; i < list1.Count; i++)
{
Console.WriteLine("list1.Number => " + list1[i].Number);
Console.WriteLine("list1.Person => " + list1[i].Person);
}
List<SampleData> list2 = new List<SampleData>(list1.FindAll(m => m.Number == 1).Select(x => new SampleData().ShallowCopy())).ToList();
for (int i = 0; i < list2.Count; i++)
{
list2[i].Person = "Person " + list2[i].Number;
Console.WriteLine("list2.Number => " + list2[i].Number);
Console.WriteLine("list2.Person => " + list2[i].Person);
}
SampleData sd = list2.Find(s => s.Number == 1);
Console.WriteLine("Apartment Number" + sd.apartment.BuildingLetter); // <<<<------------------- THROWING NULL EXCEPTION FOR APARTMENT
Console.WriteLine("-------AFTER MODIFYING NEW LIST----LIST1.Person SHOULD BE NULL---");
for (int i = 0; i < list1.Count; i++)
{
Console.WriteLine("--list1.Number => " + list1[i].Number);
Console.WriteLine("--list1.Person => " + list1[i].Person);
}
for (int i = 0; i < list2.Count; i++)
{
Console.WriteLine("--list2.Number => " + list2[i].Number);
Console.WriteLine("--list2.Person => " + list2[i].Person);
}
Console.ReadLine();
System.Environment.Exit(0);
}
}
class SampleData
{
public int Number { get; set; }
public String Person { get; set; }
public Apartment apartment { get; set; }
public static List<SampleData> MakeList(int count)
{
List<SampleData> l = new List<SampleData>();
for (int i = 0; i < count; i++)
{
SampleData d = new SampleData();
d.apartment = new Apartment { RoomNumber = i, BuildingLetter = "letter-" + i };
d.Number = i;
l.Add(d);
}
return l;
}
public SampleData ShallowCopy()
{
return (SampleData)this.MemberwiseClone();
}
}
class Apartment
{
public int RoomNumber { get; set; }
public String BuildingLetter { get; set; }
}
You can use . AsNoTracking() Method in case Entity Query wheen select from DbContext or ObjectContext
List<SampleData> list2 = new List<SampleData>(list1.Where(m => m.Number == 1).AsNoTracking().ToList());
or use a Copy Contractor like that
class SampleData
{
public int Number { get; set; }
public String Person { get; set; }
public SampleData(SampleData obj)
{
This.Number=obj.Number;
This.Person=obj.Person;
..
..
}
public static List<SampleData> MakeList(int count)
{
List<SampleData> l = new List<SampleData>();
for (int i = 0; i < count; i++)
{
SampleData d = new SampleData();
d.Number = i;
l.Add(d);
}
return l;
}
}
Then
List<SampleData> list2 = new List<SampleData>(list1.Where(m => m.Number == 1).Select(x=>new SampleData(x)).ToList());
ShallowCopy is your friend.
Define a ShallowCopy() method within your SampleData class like this.
class SampleData
{
public int Number { get; set; }
public String Person { get; set; }
public static List<SampleData> MakeList(int count)
{
List<SampleData> l = new List<SampleData>();
for (int i = 0; i < count; i++)
{
SampleData d = new SampleData();
d.Number = i;
l.Add(d);
}
return l;
}
public SampleData ShallowCopy()
{
return (SampleData)this.MemberwiseClone();
}
}
Then populate list2 as follows...
List<SampleData> list2 = new List<SampleData>();
foreach (SampleData sd in list1.Where(m => m.Number == 1))
{
list2.Add(sd.ShallowCopy());
}
Given: LDAP stores location of users.
How do I drive their timezones using their location? Any pointers are accepted, Java language preferred.
Thanks in advance.
This depends on information the "location" contains? You'd somehow need to map the location to a timezone name, preferably the Olson style timezone names, because they are more detailed and easier to map, as they are locations themselves.
If it's an approximate addres (like country and city or so) then several geolocation services do include timezones in their information, so you can call these services and see.
If it's a geolocation with latitude and longitude then a site called Earthtools can give you the timezone. http://www.earthtools.org/webservices.htm#timezone
There is this database that provides mappings from cities and countries to timezones: http://citytimezones.info/cms/pending_requests.htm
Unfortunately it uses Windows timezone names, but you can this data http://unicode.org/repos/cldr/trunk/common/supplemental/windowsZones.xml from Unicode.org to map between Windows timezone names and the Olson TZ names.
I haven't actually done this but the following should work:
You can first use GeoGoogle java library to get the longitude/latitude from the city-state-country.
Next, you can use EarthTools (and some java code of your own) mentioned by Lennart to get the timezone :)
We are using the MaxMind GeoIP database to get information regarding the location of a user. They have a paid version (99.8% accuracy) as well as a free version (99.5% accuracy).
They also provide you with APIs in Java, C, PHP etc that will enable you to query its database which you can download and keep locally (updates provided each month). The database provides you info regarding the client city, state, country etc on the basis of IP addresses.
Hope this helps.
Try this code for use Google Time Zone API from Java:
String get_xml_server_reponse(String server_url){
URL xml_server = null;
String xmltext = "";
InputStream input;
try {
xml_server = new URL(server_url);
try {
input = xml_server.openConnection().getInputStream();
final BufferedReader reader = new BufferedReader(new InputStreamReader(input));
final StringBuilder sBuf = new StringBuilder();
String line = null;
try {
while ((line = reader.readLine()) != null)
{
sBuf.append(line);
}
}
catch (IOException e)
{
Log.e(e.getMessage(), "XML parser, stream2string 1");
}
finally {
try {
input.close();
}
catch (IOException e)
{
Log.e(e.getMessage(), "XML parser, stream2string 2");
}
}
xmltext = sBuf.toString();
} catch (IOException e1) {
e1.printStackTrace();
}
} catch (MalformedURLException e1) {
e1.printStackTrace();
}
return xmltext;
}
private String get_UTC_Datetime_from_timestamp(long timeStamp){
try{
Calendar cal = Calendar.getInstance();
TimeZone tz = cal.getTimeZone();
int tzt = tz.getOffset(System.currentTimeMillis());
timeStamp -= tzt;
// DateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss",Locale.getDefault());
DateFormat sdf = new SimpleDateFormat();
Date netDate = (new Date(timeStamp));
return sdf.format(netDate);
}
catch(Exception ex){
return "";
}
}
class NTP_UTC_Time
{
private static final String TAG = "SntpClient";
private static final int RECEIVE_TIME_OFFSET = 32;
private static final int TRANSMIT_TIME_OFFSET = 40;
private static final int NTP_PACKET_SIZE = 48;
private static final int NTP_PORT = 123;
private static final int NTP_MODE_CLIENT = 3;
private static final int NTP_VERSION = 3;
// Number of seconds between Jan 1, 1900 and Jan 1, 1970
// 70 years plus 17 leap days
private static final long OFFSET_1900_TO_1970 = ((365L * 70L) + 17L) * 24L * 60L * 60L;
private long mNtpTime;
public boolean requestTime(String host, int timeout) {
try {
DatagramSocket socket = new DatagramSocket();
socket.setSoTimeout(timeout);
InetAddress address = InetAddress.getByName(host);
byte[] buffer = new byte[NTP_PACKET_SIZE];
DatagramPacket request = new DatagramPacket(buffer, buffer.length, address, NTP_PORT);
buffer[0] = NTP_MODE_CLIENT | (NTP_VERSION << 3);
writeTimeStamp(buffer, TRANSMIT_TIME_OFFSET);
socket.send(request);
// read the response
DatagramPacket response = new DatagramPacket(buffer, buffer.length);
socket.receive(response);
socket.close();
mNtpTime = readTimeStamp(buffer, RECEIVE_TIME_OFFSET);
} catch (Exception e) {
// if (Config.LOGD) Log.d(TAG, "request time failed: " + e);
return false;
}
return true;
}
public long getNtpTime() {
return mNtpTime;
}
/**
* Reads an unsigned 32 bit big endian number from the given offset in the buffer.
*/
private long read32(byte[] buffer, int offset) {
byte b0 = buffer[offset];
byte b1 = buffer[offset+1];
byte b2 = buffer[offset+2];
byte b3 = buffer[offset+3];
// convert signed bytes to unsigned values
int i0 = ((b0 & 0x80) == 0x80 ? (b0 & 0x7F) + 0x80 : b0);
int i1 = ((b1 & 0x80) == 0x80 ? (b1 & 0x7F) + 0x80 : b1);
int i2 = ((b2 & 0x80) == 0x80 ? (b2 & 0x7F) + 0x80 : b2);
int i3 = ((b3 & 0x80) == 0x80 ? (b3 & 0x7F) + 0x80 : b3);
return ((long)i0 << 24) + ((long)i1 << 16) + ((long)i2 << 8) + (long)i3;
}
/**
* Reads the NTP time stamp at the given offset in the buffer and returns
* it as a system time (milliseconds since January 1, 1970).
*/
private long readTimeStamp(byte[] buffer, int offset) {
long seconds = read32(buffer, offset);
long fraction = read32(buffer, offset + 4);
return ((seconds - OFFSET_1900_TO_1970) * 1000) + ((fraction * 1000L) / 0x100000000L);
}
/**
* Writes 0 as NTP starttime stamp in the buffer. --> Then NTP returns Time OFFSET since 1900
*/
private void writeTimeStamp(byte[] buffer, int offset) {
int ofs = offset++;
for (int i=ofs;i<(ofs+8);i++)
buffer[i] = (byte)(0);
}
}
String get_time_zone_time(GeoPoint gp){
String erg = "";
String raw_offset = "";
String dst_offset = "";
double Longitude = gp.getLongitudeE6()/1E6;
double Latitude = gp.getLatitudeE6()/1E6;
// String request = "http://ws.geonames.org/timezone?lat="+Latitude+"&lng="+ Longitude+ "&style=full";
long tsLong = 0; // System.currentTimeMillis()/1000;
NTP_UTC_Time client = new NTP_UTC_Time();
if (client.requestTime("pool.ntp.org", 2000)) {
tsLong = client.getNtpTime();
}
if (tsLong != 0)
{
tsLong = tsLong / 1000;
// https://maps.googleapis.com/maps/api/timezone/xml?location=39.6034810,-119.6822510×tamp=1331161200&sensor=true
String request = "https://maps.googleapis.com/maps/api/timezone/xml?location="+Latitude+","+ Longitude+ "×tamp="+tsLong +"&sensor=true";
String xmltext = get_xml_server_reponse(request);
if(xmltext.compareTo("")!= 0)
{
int startpos = xmltext.indexOf("<TimeZoneResponse");
xmltext = xmltext.substring(startpos);
XmlPullParser parser;
try {
parser = XmlPullParserFactory.newInstance().newPullParser();
parser.setInput(new StringReader (xmltext));
int eventType = parser.getEventType();
String tagName = "";
while(eventType != XmlPullParser.END_DOCUMENT) {
switch(eventType) {
case XmlPullParser.START_TAG:
tagName = parser.getName();
break;
case XmlPullParser.TEXT :
if (tagName.equalsIgnoreCase("raw_offset"))
if(raw_offset.compareTo("")== 0)
raw_offset = parser.getText();
if (tagName.equalsIgnoreCase("dst_offset"))
if(dst_offset.compareTo("")== 0)
dst_offset = parser.getText();
break;
}
try {
eventType = parser.next();
} catch (IOException e) {
e.printStackTrace();
}
}
} catch (XmlPullParserException e) {
e.printStackTrace();
erg += e.toString();
}
}
int ro = 0;
if(raw_offset.compareTo("")!= 0)
{
float rof = str_to_float(raw_offset);
ro = (int)rof;
}
int dof = 0;
if(dst_offset.compareTo("")!= 0)
{
float doff = str_to_float(dst_offset);
dof = (int)doff;
}
tsLong = (tsLong + ro + dof) * 1000;
erg = get_UTC_Datetime_from_timestamp(tsLong);
}
return erg;
}
And use it with:
GeoPoint gp = new GeoPoint(39.6034810,-119.6822510);
String Current_TimeZone_Time = get_time_zone_time(gp);
Implement Biginteger Multiply
use integer array to store a biginteger
like 297897654 will be stored as {2,9,7,8,9,7,6,5,4}
implement the multiply function for bigintegers
Expamples: {2, 9, 8, 8, 9, 8} * {3,6,3,4,5,8,9,1,2} = {1,0,8,6,3,7,1,4,1,8,7,8,9,7,6}
I failed to implement this class and thought it for a few weeks, couldn't get the answer.
Anybody can help me implement it using C#/Java?
Thanks a lot.
Do you know how to do multiplication on paper?
123
x 456
-----
738
615
492
-----
56088
I would just implement that algorithm in code.
C++ Implementation:
Source Code:
#include <iostream>
using namespace std;
int main()
{
int a[10] = {8,9,8,8,9,2};
int b[10] = {2,1,9,8,5,4,3,6,3};
// INPUT DISPLAY
for(int i=9;i>=0;i--) cout << a[i];
cout << " x ";
for(int i=9;i>=0;i--) cout << b[i];
cout << " = ";
int c[20] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
for(int i=0;i<10;i++)
{
int carry = 0;
for(int j=0;j<10;j++)
{
int t = (a[j] * b[i]) + c[i+j] + carry;
carry = t/10;
c[i+j] = t%10;
}
}
// RESULT DISPLAY
for(int i=19;i>=0;i--) cout << c[i];
cout << endl;
}
Output:
0000298898 x 0363458912 = 00000108637141878976
There is a superb algorithm called Karatsuba algorithm..Here
Which uses divide and conquer startegy..Where you can multiply large numbers..
I have implemented my it in java..
Using some manipulation..
package aoa;
import java.io.*;
public class LargeMult {
/**
* #param args the command line arguments
*/
public static void main(String[] args) throws IOException
{
// TODO code application logic here
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter 1st number");
String a=br.readLine();
System.out.println("Enter 2nd number");
String b=br.readLine();
System.out.println("Result:"+multiply(a,b));
}
static String multiply(String t1,String t2)
{
if(t1.length()>1&&t2.length()>1)
{
int mid1=t1.length()/2;
int mid2=t2.length()/2;
String a=t1.substring(0, mid1);//Al
String b=t1.substring(mid1, t1.length());//Ar
String c=t2.substring(0, mid2);//Bl
String d=t2.substring(mid2, t2.length());//Br
String s1=multiply(a, c);
String s2=multiply(a, d);
String s3=multiply(b, c);
String s4=multiply(b, d);
long ans;
ans=Long.parseLong(s1)*(long)Math.pow(10,
b.length()+d.length())+Long.parseLong(s3)*(long)Math.pow(10,d.length())+
Long.parseLong(s2)*(long)Math.pow(10, b.length())+Long.parseLong(s4);
return ans+"";
}
else
{
return (Integer.parseInt(t1)*Integer.parseInt(t2))+"";
}
}
}
I hope this helps!!Enjoy..
Give the number you want to multiply in integer type array i.e. int[] one & int[] two.
public class VeryLongMultiplication {
public static void main(String args[]){
int[] one={9,9,9,9,9,9};
String[] temp=new String[100];
int c=0;
String[] temp1=new String[100];
int c1=0;
int[] two={9,9,9,9,9,9};
int car=0,mul=1; int rem=0; int sum=0;
String str="";
////////////////////////////////////////////
for(int i=one.length-1;i>=0;i--)
{
for(int j=two.length-1;j>=0;j--)
{
mul=one[i]*two[j]+car;
rem=mul%10;
car=mul/10;
if(j>0)
str=rem+str;
else
str=mul+str;
}
temp[c]=str;
c++;
str="";
car=0;
}
////////////////////////////////////////
for(int jk=0;jk<c;jk++)
{
for(int l=c-jk;l>0;l--)
str="0"+str;
str=str+temp[jk];
for(int l=0;l<=jk-1;l++)
str=str+"0";
System.out.println(str);
temp1[c1]=str;
c1++;
str="";
}
///////////////////////////////////
String ag="";int carry=0;
System.out.println("========================================================");
for(int jw=temp1[0].length()-1;jw>=0;jw--)
{
for(int iw=0;iw<c1;iw++)
{
int x=temp1[iw].charAt(jw)-'0';
sum+=x;
}
sum+=carry;
int n=sum;
sum=n%10;carry=n/10;
ag=sum+ag;
sum=0;
}
System.out.println(ag);
}
}
Output:
0000008999991
0000089999910
0000899999100
0008999991000
0089999910000
0899999100000
______________
0999998000001
If you do it the long-hand way, you'll have to implement an Add() method too to add up all the parts at the end. I started there just to get the ball rolling. Once you have the Add() down, the Multipy() method gets implemented along the same lines.
public static int[] Add(int[] a, int[] b) {
var maxLen = (a.Length > b.Length ? a.Length : b.Length);
var carryOver = 0;
var result = new List<int>();
for (int i = 0; i < maxLen; i++) {
var idx1 = a.Length - i - 1;
var idx2 = b.Length - i - 1;
var val1 = (idx1 < 0 ? 0 : a[idx1]);
var val2 = (idx2 < 0 ? 0 : b[idx2]);
var addResult = (val1 + val2) + carryOver;
var strAddResult = String.Format("{0:00}", addResult);
carryOver = Convert.ToInt32(strAddResult.Substring(0, 1));
var partialAddResult = Convert.ToInt32(strAddResult.Substring(1));
result.Insert(0, partialAddResult);
}
if (carryOver > 0) result.Insert(0, carryOver);
return result.ToArray();
}
Hint: use divide-and-conquer to split the int into halves, this can effectively reduce the time complexity from O(n^2) to O(n^(log3)). The gist is the reduction of multiplication operations.
I'm posting java code that I wrote. Hope, this will help
import org.junit.Test;
import static org.junit.Assert.*;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
/**
* Created by ${YogenRai} on 11/27/2015.
*
* method multiply BigInteger stored as digits in integer array and returns results
*/
public class BigIntegerMultiply {
public static List<Integer> multiply(int[] num1,int[] num2){
BigInteger first=new BigInteger(toString(num1));
BigInteger result=new BigInteger("0");
for (int i = num2.length-1,k=1; i >=0; i--,k=k*10) {
result = (first.multiply(BigInteger.valueOf(num2[i]))).multiply(BigInteger.valueOf(k)).add(result);
}
return convertToArray(result);
}
private static List<Integer> convertToArray(BigInteger result) {
List<Integer> rs=new ArrayList<>();
while (result.intValue()!=0){
int digit=result.mod(BigInteger.TEN).intValue();
rs.add(digit);
result = result.divide(BigInteger.TEN);
}
Collections.reverse(rs);
return rs;
}
public static String toString(int[] array){
StringBuilder sb=new StringBuilder();
for (int element:array){
sb.append(element);
}
return sb.toString();
}
#Test
public void testArray(){
int[] num1={2, 9, 8, 8, 9, 8};
int[] num2 = {3,6,3,4,5,8,9,1,2};
System.out.println(multiply(num1, num2));
}
}