CODEWITHSUNDEEP
java
Florian Firlus
Florian Firlus

Reputation: 21

Why is the output of this function 1?

I need an explanation of why this code prints "1", I'm taking my final exam tomorrow and this is a practice question that I cannot answer.... Any input is greatly appreciated! 

public class Test {
  public static void main(String[] args) {
    int[][] values = {{3, 4, 5, 1}, {33, 6, 1, 2}};
    int v = values[0][0];
    for (int[] list : values)
      for (int element : list)
        if (v > element)
          v = element;

    System.out.print(v);
  }
}

Upvotes: 0

Views: 218

Answers (4)

Wayne
Wayne

Reputation: 60414

What do you think this code is supposed to do? Currently, it's printing the lowest number found. Why? Because for each element it performs the following check:

if (v > element)
    v = element;

...where

v = <the smallest number found so far>
  • The first time through the loop the smallest number found so far is the first element -- values[0][0] -- because, well, it is the smallest number found at that point, since we haven't yet looked at any elements.
  • Each time through the inner loop we compare the smallest number found so far to the current element. If the smallest number found so far is larger than the current element, then the current element must be the smallest number found so far.
  • On each subsequent iteration, this invariant does not change. At the end of each iteration v contains the smallest number seen so far.

I strongly recommend stepping through the code in a debugger or (even better) writing down the steps on paper, testing the loop invariants at each iteration.

Upvotes: 1

Eduardo Iglesias
Eduardo Iglesias

Reputation: 1066

Well we need to check step by step

First

you got you main 2 dimensions array

int[][] values = {{3, 4, 5, 1}, {33, 6, 1, 2}};

Then you assign to a var V int. With the data of [0][0].

Note that values[0] = 3,4,5,1
values[0][0] = 3
int v = values[0][0];

Then the 2 for cheek each value in the array. First in values[0-1] and then values[][0-3]

for (int[] list : values)
      for (int element : list)

Finally you check if the V is greater than the new values you get. IF it is it substitute 

if (v > element)
          v = element;

this code get's you the smallest number in the array. The first number. If you have two 1 it will take the first one.

I hope it help

Upvotes: 1

Filip Ros&#233;en
Filip Ros&#233;en

Reputation: 63797

Because the code below will give you the smallest value in your nested array values, which is indeed 1 in your code.

if (v > element)
  v = element;

If v is larger than current element (ie. element is smaller than v), assign element to v.

Upvotes: 6

Will
Will

Reputation: 20235

You are iterating through all the elements in the array and setting v to the element if it is greater than the element if (v > element) v = element;. Therefore, you will end up with the smallest value, which is 1.

Upvotes: 1

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