[英]Sort an array From highest to lowest
我正在嘗試用 Java 對數組進行排序,我只想要前 3 個值。
// A:55,B:45,C:5,D:35,E:35,F:1
int a[] = {A,B,C,D,E,F};
float first =0;
float second=0;
float third =0;
for (int i=0; i<a.length; i++){
if(first <= a[i]){
first=a[i];
}
}System.out.println("first largest is "+first);
for (int j=0; j<a.length; j++){
if(a[j] <=first && a[j] > second){
second = a[j];
}
}System.out.println("second largest is "+second);
for (int k=0;k<a.length; k++){
if(a[k]<=second && a[k]>third){
third =a[k];
}
}System.out.println("third largest is "+third);
這里的另一件事是,如果 A 和 B 相等,它應該給我 A,如果 D 和 E 相等,它應該提供 D 作為答案。 所以最終答案應該是ABD。
您可以在變量first,second,third中存儲索引而不是值
我很快重寫了代碼,它不是最佳的,但我認為它可以提供幫助
public static void main(String[] args) {
char names[] = {'A', 'B', 'C', 'D', 'E', 'F'};
int values[] = {55, 45, 5, 35, 35, 1, Integer.MIN_VALUE};
int first = values.length - 1;
int second = values.length - 1;
int third = values.length - 1;
for (int i = 0; i < values.length; i++) {
if (values[first] < values[i]) {
first = i;
}
}
System.out.println("first largest is " + names[first]);
for (int j = 0; j < values.length; j++) {
if (j != first && values[second] < values[j]) {
second = j;
}
}
System.out.println("second largest is " + names[second]);
for (int k = 0; k < values.length; k++) {
if (k != first && k != second && values[third] < values[k]) {
third = k;
}
}
System.out.println("third largest is " + names[third]);
}
我加入了Integer.MIN_VALUE的,以列表的末尾是作為變量的初始指數第一,第二和第三你CAD 0替換它,如果你需要,但它永遠不會與負數的工作,然后
Max Heap數據結構是你的朋友:
public static void main(String[] args) {
char[] arr = { 'A', 'B', 'C', 'D', 'E', 'F' };
List<Character> sorted = sortAngGetTopThree(arr);
System.out.println("first largest is " + sorted.get(0));
System.out.println("second largest is " + sorted.get(1));
System.out.println("third largest is " + sorted.get(2));
}
public static List<Character> sortAngGetTopThree(char... arr) {
Map<Character, Integer> map = Map.of('A', 55, 'B', 45, 'C', 5, 'D', 35, 'E', 35, 'F', 1);
Comparator<Character> sortByValueAndLetterDesc = (one, two) -> {
int res = Integer.compare(map.get(two), map.get(one)); // sort by number desc first
return res == 0 ? Character.compare(one, two) : res; // sort by letter asc second
};
Queue<Character> maxHeap = new PriorityQueue<>(sortByValueAndLetterDesc);
for (char ch : arr)
maxHeap.add(ch);
List<Character> res = new ArrayList<>(3);
for (int i = 0; i < 3 && !maxHeap.isEmpty(); i++)
res.add(maxHeap.remove());
return res;
}
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