Thread: Second largest

Hi.

I'm trying to find the largest and the second largest number in vector. But I can't.

Can you help?

public class Minmax{
  public static void main(String[] args) {
 
    //int min = Integer.MIN_VALUE;
    int max = Integer.MAX_VALUE;
    int max2 =Integer.MAX_VALUE;
 
 
    while (!StdIn.isEmpty()) {
      int N = StdIn.readInt();
      if (N > max){
        max2=max;//storing the old max
	max = N;//the new max
		}
 
      else if (N>max2 && N<max) {//if the number is between new max and the old max
        max2=N;
      }
	}
	StdOut.println(max2 + " " + max);
  }
}

Error message:
C:\>java Minmax 2 22 5 55 6 66
^Z
2147483647 2147483647

C:\Users>java Minmax
55 2 66 2 88 5 99
^Z
2147483647 2147483647

Remind me, what is StdIn? I think I remember it from a book I read a long time ago, but I've forgotten.

It looks like you meant to use the command line input that is saved in the args[] array rather than StdIn. Is that right?

StdIn is used in my textbook, Introduction to programming in java. It's a library thing for all kinds of inputs.

Your right. But I think I can use it like that and press ctrl+enter

--- Update ---

This is the ''older'' version. As you can see it prints out the highest value twice.
I'm trying to fix that.

public class Minmax {
  public static void main(String[] args) {
 
    int min = Integer.MAX_VALUE;
    int max = Integer.MIN_VALUE;
    int max2 =Integer.MIN_VALUE;
 
    while (!StdIn.isEmpty()) {
      int N = StdIn.readInt();
      if (N > max) {
        max = N;
	max2=max;
      }
      if (N < max && N>max2) {
        max2 = N;
      }
    }
    StdOut.println(max2 + " " + max);
  }
}

C:\java Minmax
5
55
66
55
556
5
557
^Z
557 557

It's interesting that you changed the beginning values to MAX from MIN. If you want to find a large number from a collection, you start by comparing it to a smaller number, not a number that it couldn't possibly be larger than.

I also don't see the purpose of your else statement. Try changing the initial values back to MIN, eliminate the else clause, and I think you'll be there.

It did not work out for me.

How about this. Find the three largest numbers and print them out.

public class Minmax2 {
  public static void main(String[] args) {
 
    int max = Integer.MIN_VALUE;
    int max1= Integer.MIN_VALUE;
    int max2 =Integer.MIN_VALUE;
 
    while (!StdIn.isEmpty()) {
      int N = StdIn.readInt();
      if (max<N) {
        max2 = max1;
		max1=max;
		max=N;
		}
		if (max1<N) {
			max2= max1;
			max1 =N;
			}
			else if(max2<N){
				max2=N;
				}
    }
  StdOut.println(max2 + " " + max1 + " " + max);
}}

C:\>java Minmax2
55
66
88
-1
66
67
68
^Z
68 88 88

You're right, I over simplified, but why did you change the problem?

Here's my for loop using an array that contains the same numbers you used in the same order for the 2 largest numbers, not 3:

int[] numbers = { 55, 66, 88, -1, 66, 67, 68 };
 
for ( int i = 0 ; i < numbers.length ; i++ )
{
    int N = numbers[i];
    if (N > max)
    {
        max2=max;//storing the old max
        max = N;//the new max
    }
 
    // find values between current max and max2 for new max2
    if ( N < max && N > max2 )
    {
        max2 = N;
    }
}

I thought it was more fun like this. I saw it on stackverflow.

Thanks for the ongoing support.