How to find the position of the highest and second highest value in an array in java

Question

Let's assume that we have an array with integer numbers. For Example perimeter={180,50,65,78,90,5,150,2,35} and i want to find the highest value and its position in the array and the second value and its position in the array.

public class FindTopTwo {

public static void main(String[] args) {
    double perimeter[]= {180,50,65,78,90,5,150,2,35};
    double megisto, megisto2;
    int i;
    megisto=perimeter[0];
    megisto2=perimeter[0];
    for (i=0;i<perimeter.length;i++) {
        if (perimeter[i]>megisto) {
            megisto2=megisto;
            megisto=perimeter[i];}
        else if (perimeter[i]>megisto2) {
            megisto2=perimeter[i];
        }
    }
    System.out.println("the first is:"+megisto+"the second highest value is "+megisto2);    

   }

}

Answer 1

Just keep track of their indexes( i ) as their values change:

public static void main(String[] args) {
    double perimeter[]= {180,50,65,78,90,5,150,2,35};
    double megisto, megisto2;
    megisto=perimeter[0];
    int megistoIndex = 0;

    megisto2=perimeter[0];

    int megisto2Index = 0;

    for (int i=0;i<perimeter.length;i++) {
        if (perimeter[i]>megisto) {
          megistoIndex = i;
          megisto = perimeter[i];
        } else if (perimeter[i] < megisto && perimeter[i] > megisto2) {
          megisto2Index = i;
          megisto2 = perimeter[i];
        }

    }
    System.out.println(String.format("the first is: %d at index %d. The second highest value is %d at index %d", megisto, megistoIndex, megisto2, megisto2Index));
}

Answer 2

set highestIndex = -1;
set nextHighestIndex = -1;

for every element of perimiter:

  if highestIndex = -1:
    set highestIndex = i;
  else if perimiter[i] > perimiter[highestIndex]
    set nextHighestIndex = highestIndex;
    set highestIndex = i;
  else if perimiter[i] > perimieter[nextHighestIndex]
    set nextHighestIndex = i;

If the array is not empty, you will find the highest value in perimiter[highestIndex]

If the array has at least two distinct values, you will find the second highest value in perimeter[nextHighestIndex]