如何在 java 的數組中找到最高和第二高值的 position

Question

假設我們有一個包含 integer 數字的數組。 例如周長={180,50,65,78,90,5,150,2,35}，我想在數組中找到最大值及其 position，在數組中找到第二個值及其 position。

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

當它們的值發生變化時，只需跟蹤它們的索引（ i ）：

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;

如果數組不為空，則會在 perimiter[highestIndex] 中找到最大值

如果數組至少有兩個不同的值，您將在 perimeter[nextHighestIndex] 中找到第二高的值