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

Question

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"

• Guy Gavriely: stackoverflow.com/questions/15995458/…
• extraneon: ouch. Index counting starts at 0, not 1. As a condition you should use i < tenIntArray.length and not !=, just to be safe when you start using doubles or floats.
• Bernhard Barker: @extraneon It's not "just to be safe", it's the more logical, generally accepted way of doing things.

Answer 1

This figure should be helpful :

enter image description here

Then to answer your question, what would you do on paper ?

1. Create and initialize the min value at tenIntArray[0]
2. 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])
3. Loop through the elements of your array
4. 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
5. You're done

Writing the algorithm should be straightforward now.

Answer 2

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;
 }
}

Answer 3

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();

• Srikanth R: May I know the time complexity of this approach?
• J.R: Will be O(n) I guess

Answer 4

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

Answer 5

 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);

Answer 6

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; 
}

Answer 7

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");

• user3101937: Yes I did. can you tell me about the fault?
• Alexis C.: It's find the smallest but not the correct index. For example with the input int [] tenIntArray = {1,-8,2,2,0,-15};, you will increment the index variable 3 times. But that won't give you the correct index of the minimum value in the array. You have to keep track of the current index, and update another variable when you have found a smallest value (like you did for small).
• user3101937: ah I got that.thanks.if I start with int index = -1; , is that correct?
• Jens Kooij: You should increase i outside of the if statement, because even if the current index is not the smallest, it should increase the i for keeping track of the current index.