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Finding Similar Birthday through structure data

Hey guys I am trying to get the number of people who have the same birthday but this solution isn't working.This program is showing 0.0% .Please help me ...!.
public double calculate(int size, int count) {
int matches = 0;//initializing an integer variable
boolean out = false;
List<Integer> days=new ArrayList<Integer>();// creating arraylist name days of type int
for (int j = 0; j <count; j++) {
for (int i = 0; i < size; i++) {// initializing for loop till less than size
Random rand = new Random(); // creating an object of random function
int Brday = rand.nextInt(364) + 0;//initializing the limit of randomc number chozen
days.add(Brday); //adding values to arraylist
}
for (int l = 0; l < size; l++) {
int temp = l;//assigning value of l to a variable
for (int k = l + 1; k < size; k++) {
if (days.get(k) == temp) {// check statement to check values are same
matches++;//incrementing variable
out = true;
mOut.print("Count does have same birthday" + matches);
break;
} else {
mOut.print("does not have same birthday");
}
}
if (out) {
out = false;
break;
}
}
}
double prob = (double) matches / count;
mOut.print("The probability for two students to share a birthday is " + prob*100 + ".");
return prob;//returning double value of the function
}

Actually, you get either 0 percent or 100 percent with your code. Try invoking it with calculate(100, 100) if you want to see.
There are two things that are wrong in this code. First, if you run the simulation more than once (count > 1) then you never clear the list of birthdays before the second iteration.
Your method should begin with:
public double calculate(int size, int count) {
int matches = 0;
boolean out = false;
List<Integer> days;
for (int j = 0; j <count; j++) {
days = new ArrayList<Integer>();
Secondly, you're not comparing two birthdays but you're comparing a birthday to the index in the list.
This line:
int temp = l;//assigning value of l to a variable
Should read:
int temp = days.get(l); // Remember the birthday at index l
With those changes you'll get a much better result.

Selection sort for doubles in java

I have written the selection sort method before for ints, but right now I am working with an array of doubles. I have tried changing the variables to doubles, but I am still getting a "Cannot convert from double to int". Any help is appreciated, thanks!
//Original selection sort for ints
public static void selectionSort (int... arr)
{
int i = 0, j = 0, smallest = 0;
int temp = 0;
for (i = 0;i<arr.length - 1;i++)
{
smallest = i;
for (j = 1; j<arr.length - 1; j++)
{
if (arr[j]<arr[smallest])
smallest = j;
}
temp = arr[smallest];
arr[smallest] = arr[i];
arr[i] = temp;
}
}
//Attempted selection sort with doubles
public static void selectionSort (double...arr )
{
double i = 0.0, j = 0.0, smallest = 0.0;
double temp = 0.0;
for (i = 0.0;i<arr.length - 1.0;i++)
{
smallest = i;
for (j = 1.0; j<arr.length - 1.0; j++)
{
if (arr[j]<arr[smallest]) //error here with smallest and j
smallest = j;
}
temp = arr[smallest]; //error here with smallest
arr[smallest] = arr[i]; //error here with smallest and i
arr[i] = temp; //error here with i
}
}

The problem is that you've also used double for indexing the arrays. So try this instead:
public static void selectionSort (double...arr)
{
int i = 0, j = 0, smallest = 0;
double temp = 0.0;
for (i = 0; i < arr.length - 1; i++)
{
smallest = i;
for (j = 1; j < arr.length - 1; j++)
{
if (arr[j] < arr[smallest])
smallest = j;
}
temp = arr[smallest];
arr[smallest] = arr[i];
arr[i] = temp;
}
}
As you can see you still have doubles as parameter, and the temp-value and arr-array are also still doubles, but the indexes that are used for the array are ints.
Indexes are always int. For example, when we have an array of Strings, we still use ints for the indexes:
String[] sArray = {
"word1",
"word2",
"word3"
}
int index = 1;
String result = sArray[index]; // As you can see we use an int as index, and the result is a String
// In your case, the index is still an int, but the result is a double

Why did you change the for loop to doubles?
for (i = 0.0;i<arr.length - 1.0;i++)
It does only work with int's for the indexes of the arrays.

You have to use subscript value as int check out with that. Use like this
int i = 0,j =0,smallest = 0;
access array values using these

Find smallest integer value in array list in Java without Arrays.sort

How can I find the smallest value in a int array without changing the array order?
code snippet:
int[] tenIntArray = new int [10];
int i, userIn;
Scanner KyBdIn = new Scanner(System.in);
System.out.println("Please enter 10 integer numbers ");
for(i = 0; i < tenIntArray.length; i++){
System.out.println("Please enter integer " + i);
userIn = KyBdIn.nextInt();
tenIntArray[i] = userIn;
}
I am not sure how I can find the smallest array value in the tenIntArray and display the position
For example the array holds - [50, 8, 2, 3, 1, 9, 8, 7 ,54, 10]
The output should say "The smallest value is 1 at position 5 in array"

This figure should be helpful :
Then to answer your question, what would you do on paper ?
Create and initialize the min value at tenIntArray[0]
Create a variable to hold the index of the min value in the array and initialize it to 0 (because we said in 1. to initialize the min at tenIntArray[0])
Loop through the elements of your array
If you find an element inferior than the current min, update the minimum value with this element and update the index with the corresponding index of this element
You're done
Writing the algorithm should be straightforward now.

Try this:
//Let arr be your array of integers
if (arr.length == 0)
return;
int small = arr[0];
int index = 0;
for (int i = 0; i < arr.length; i++) {
if (arr[i] < small) {
small = arr[i];
index = i;
}
}

Using Java 8 Streams you can create a Binary operator which compares two integers and returns smallest among them.
Let arr is your array
int[] arr = new int[]{54,234,1,45,14,54};
int small = Arrays.stream(arr).reduce((x, y) -> x < y ? x : y).getAsInt();

The method I am proposing will find both min and max.
public static void main(String[] args) {
findMinMax(new int[] {10,40,50,20,69,37});
}
public static void findMinMax(int[] array) {
if (array == null || array.length < 1)
return;
int min = array[0];
int max = array[0];
for (int i = 1; i <= array.length - 1; i++) {
if (max < array[i]) {
max = array[i];
}
if (min > array[i]) {
min = array[i];
}
}
System.out.println("min: " + min + "\nmax: " + max);
}
Obviously this is not going to one of the most optimized solution but it will work for you. It uses simple comparison to track min and max values. Output is:
min: 10
max: 69

int[] input = {12,9,33,14,5,4};
int max = 0;
int index = 0;
int indexOne = 0;
int min = input[0];
for(int i = 0;i<input.length;i++)
{
if(max<input[i])
{
max = input[i];
indexOne = i;
}
if(min>input[i])
{
min = input[i];
index = i;
}
}
System.out.println(max);
System.out.println(indexOne);
System.out.println(min);
System.out.println(index);

Here is the function
public int getIndexOfMin(ArrayList<Integer> arr){
int minVal = arr.get(0); // take first as minVal
int indexOfMin = -1; //returns -1 if all elements are equal
for (int i = 0; i < arr.size(); i++) {
//if current is less then minVal
if(arr.get(i) < minVal ){
minVal = arr.get(i); // put it in minVal
indexOfMin = i; // put index of current min
}
}
return indexOfMin;
}

the first index of a array is zero. not one.
for(i = 0; i < tenIntArray.length; i++)
so correct this.
the code that you asked is :
int small = Integer.MAX_VALUE;
int i = 0;
int index = 0;
for(int j : tenIntArray){
if(j < small){
small = j;
i++;
index = i;
}
}
System.out.print("The smallest value is"+small+"at position"+ index +"in array");

Not ignoring a value?

import java.util.Scanner;
import java.util.Arrays;
public class Improved {
//I resize the array here so that it only counts inputs from the user
//I want to ignore the 0 input from the user
//I think the error happens here or in my main method
public static double[] resizeArray(double[] numbers, double size) {
double[] result = new double[(int)size];
for (int i = 0; i < Math.min(numbers.length, size); ++i) {
result[i] = numbers[i];
}
return result;
}
//compute average nothing is wrong here
public static double getAverage( double[] numbers) {
double sum = 0;
for (int i = 0; i < numbers.length; ++i)
sum += numbers[i];
double average = sum/numbers.length;
return average;
}
//SD nothing is wrong here
public static double getSD( double[] numbers, double average) {
double sd = 0;
for ( int i = 0; i < numbers.length; ++i)
sd += ((numbers[i] - average)*(numbers[i] - average)/ numbers.length);
double standDev = Math.sqrt(sd);
return standDev;
}
//maximum nothing is wrong here
public static double getMax( double[] numbers) {
double max = numbers[0];
for (int i = 1; i < numbers.length; ++i)
if (numbers[i] > max){
max = numbers[i];
}
return max;
}
//minimum nothing is wrong here
public static double getMin( double[] numbers) {
double min = numbers[0];
for (int i = 1; i < numbers.length; ++i)
if (numbers[i] < min) {
min = numbers[i];
}
return min;
}
//median value nothing is wrong here
public static double getmed( double[] numbers) {
double median;
if (numbers.length % 2 == 0)
median = (((numbers[numbers.length/2 - 1])
+ (numbers[numbers.length/2]))/2);
else
median = numbers[numbers.length/2];
return median;
}
//the problem is in the main method i think or in the call method to resize
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
double[] statArr = new double[99];
double size = 0;
int i = 0;
System.out.println("Type your numbers: ");
double number = input.nextDouble();
//I don't want the zero in the array, I want it to be excluded
while (number != 0){
statArr[i] = number;
i++;
number = input.nextDouble();
++size;
if ( size == statArr.length) {
statArr = resizeArray(statArr, statArr.length * 2);
}
++size;
}
statArr = resizeArray(statArr, size);
java.util.Arrays.sort(statArr);
double average = getAverage(statArr);
System.out.println( "The average is " + getAverage(statArr));
System.out.println( "The standard deviation is " + getSD(statArr, average));
System.out.println( "The maximum is " + getMax(statArr));
System.out.println( "The minimum is " + getMin(statArr));
}
}
// I don't have any concerns with computing the math parts, but I can't seem to make it so my array ignores the 0 that ends the while loop. In other words, I want every number included up until the user enters the number 0. Everything else is right. Thank you very much!

You have ++size twice. This means your resizeArray method won't work correctly:
double[] result = new double[(int)size];
Here you're allocating more than what you actually want. This is why you're getting zeroes in your array. Java arrays are initialized to 0 (in case of numeric primitive types).
As Giodude already commented, I suggest you using List implementations (typically ArrayList) instead of arrays everytime you can.
Also size could be declared as int altogether and avoid that cast (and save some extremely slight memory), you're not using it as a double anywhere.

find second and third maximum element array java

I have to find 1st, 2nd, and 3rd largest array. I know I could simply sort it and return array[0], array[1], array[3]. But the problem is, i need the index, not the value.
For example if i have float[] listx={8.0, 3.0, 4.0, 5.0, 9.0} it should return 4, 0, and 3.
Here's the code I have but it doesn't work:
//declaration max1-3
public void maxar (float[] listx){
float maxel1=0;
float maxel2=0;
float maxel3=0;
for (int i=0; i<listx.length; i++){
if(maxel1<listx[i])
{maxel1=listx[i];
max1=i;
}
}
listx[max1]=0; //to exclude this one in nextsearch
for (int j=0; j<listx.length; j++){
if(listx[j]>maxel2)
{maxel2=listx[j];
max2=j;
}
}
listx[max2]=0;
for (int k=0; k<listx.length; k++){
if(listx[k]>maxel3)
{maxel3=listx[k];
max3=k;
}
}
}
I get max1 right but after that all the elements turns to 0. hence max2 and max3 become 0. Please suggest me what is wrong with this solution. Thank you.

You can find the three elements using a single loop, and you don't need to modify the array.
When you come across a new largest element, you need to shift the previous largest and the previous second-largest down by one position.
Similarly, when you find a new second-largest element, you need to shift maxel2 into maxel3.
Instead of using the three variables, you might want to employ an array. This will enable you to streamline the logic, and make it easy to generalize to k largest elements.

Make 3 passes over array: on first pass find value and 1st index of maximum element M1, on second pass find value and 1st index of maximum element M2 which is lesser than M1 and on third pass find value/1st index M3 < M2.

Try this code it will work :)
public class Array
{
public void getMax( double ar[] )
{
double max1 = ar[0]; // Assume the first
double max2 = ar[0]; // element in the array
double max3 = ar[0]; // is the maximum element.
int ZERO = 0;
// Variable to store inside it the index of the max value to set it to zero.
for( int i = 0; i < ar.length; i++ )
{
if( ar[i] >= max1)
{
max1 = ar[i];
ZERO = i;
}
}
ar[ZERO] = 0; // Set the index contains the 1st max to ZERO.
for( int j = 0; j < ar.length; j++ )
{
if( ar[j] >= max2 )
{
max2 = ar[j];
ZERO = j;
}
}
ar[ZERO] = 0; // Set the index contains the 2st max to ZERO.
for( int k = 0; k < ar.length; k++ )
{
if( ar[k] >= max3 )
{
max3 = ar[k];
ZERO = k;
}
}
System.out.println("1st max:" + max1 + ", 2nd: " +max2 + ",3rd: "+ max3);
}
public static void main(String[] args)
{
// Creating an object from the class Array to be able to use its methods.
Array array = new Array();
// Creating an array of type double.
double a[] = {2.2, 3.4, 5.5, 5.5, 6.6, 5.6};
array.getMax( a ); // Calling the method that'll find the 1st max, 2nd max, and and 3rd max.
}
}

I suggest making a single pass instead of three for optimization. The code below works for me. Note that the code does not assert that listx has at least 3 elements. It is up to you to decide what should happen in case it contains only 2 elements or less.
What I like about this code is that it only does one pass over the array, which in its best case would have faster running time compared to doing three passes, with a factor proportionate to the number of elements in listx.
Assume i1, i2 and i3 store the indices of the three greatest elements in listx, and i0 is one of i1, i2 and i3 that points to the smallest element. In the beginning, i1 = i2 = i3 because we haven't found the largest elements yet. So let i0 = i1. If we find a new index j such that that listx[j] > listx[i0], we set i0 = j, replacing that old index with an index that leads to a greater element. Then we find the index among i1, i2 and i3 that now leads to the smallest element of out the three, so that we can safely discard that one in case a new large element comes along.
Note: This code is in C, so translate it to Java if you want to use it. I made sure to use similar syntax to make that easier. (I wrote it in C because I lacked a Java testing environment.)
void maxar(float listx[], int count) {
int maxidx[3] = {0};
/* The index of the 3rd greatest element
* in listx.
*/
int max_3rd = 0;
for (int i = 0; i < count; i++) {
if (listx[maxidx[max_3rd]] < listx[i]) {
/* Exchange 3rd greatest element
* with new greater element.
*/
maxidx[max_3rd] = i;
/* Find index of smallest maximum. */
for (int j = (max_3rd + 1) % 3; j != max_3rd; j = (j + 1) % 3) {
if (listx[maxidx[j]] < listx[maxidx[max_3rd]]) {
max_3rd = j;
}
}
}
}
/* `maxidx' now contains the indices of
* the 3 greatest values in `listx'.
*/
printf("3 maximum elements (unordered):\n");
for (int i = 0; i < 3; i++) {
printf("index: %2d, element: %f\n", maxidx[i], listx[maxidx[i]]);
}
}

public class ArrayExample {
public static void main(String[] args) {
int secondlargest = 0;
int thirdLargest=0;
int largest = 0;
int arr[] = {5,4,3,8,12,95,14,376,37,2,73};
for (int i = 0; i < arr.length; i++) {
if (largest < arr[i]) {
secondlargest = largest;
largest = arr[i];
}
if (secondlargest < arr[i] && largest != arr[i])
secondlargest = arr[i];
if(thirdLargest<arr[i] && secondlargest!=arr[i] && largest!=arr[i] && thirdLargest<largest && thirdLargest<secondlargest)
thirdLargest =arr[i];
}
System.out.println("Largest number is: " + largest);
System.out.println("Second Largest number is: " + secondlargest);
System.out.println("third Largest number is: " + thirdLargest);
}
}

def third_mar_array(arr):
max1=0
max2=0
max3=0
for i in range(0,len(arr)-1):
if max1<arr[i]:
max1=arr[i]
max_in1=i
arr[max_in1]=0
for j in range(0,len(arr)-1):
if max2<arr[j]:
max2=arr[j]
max_in2=j
arr[max_in2]=0
for k in range(0,len(arr)-1):
if max3<arr[k]:
max3=arr[k]
max_in3=k
#arr[max_in3]=0
return max3
n=[5,6,7,3,2,1]
f=first_array(n)
print f

import java.util.Scanner;
class Main {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int testcase = sc.nextInt();
while (testcase-- > 0) {
int sizeOfArray = sc.nextInt();
int[] arr = new int[sizeOfArray];
for (int i = 0; i < sizeOfArray; i++) {
arr[i] = sc.nextInt();
}
int max1, max2, max3;
max1 = 0;
max2 = 0;
max3 = 0;
for (int i = 0; i < sizeOfArray; i++) {
if (arr[i] > max1) {
max3 = max2;
max2 = max1;
max1 = arr[i];
}
else if (arr[i] > max2) {
max3 = max2;
max2 = arr[i];
}
else if (arr[i] > max3) {
max3 = arr[i];
}
}
System.out.println(max1 + " " + max2 + " " + max3);
}
}
}