java如何在O(1)空间中打印优先级队列的降序
我正在解决堆上的问题,我希望使用PriorityQueue按降序输出问题。
输入:
1
5 2
125787123
输出:
23787
想要的输出:
787 23
class GFG {
public static void main(String args[])throws IOException {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
int t = Integer.parseInt(br.readLine());
while(t-->0) {
// take array and kth element iput
String n_k[] = br.readLine().split(" ");
// store array size in n && kth element to find in k
int n = Integer.parseInt(n_k[0]);
int k = Integer.parseInt(n_k[1]);
// Array String input
String s[] = br.readLine().split(" ");
int d[] = new int[n];
for(int i = 0 ; i < n ; i++) {
d[i] = Integer.parseInt(s[i]);
}
PriorityQueue<Integer> minHeap = new PriorityQueue<Integer>();
// delete the minimum element in the element and just keep
// k greater element in the minHeap
for(int i = 0 ; i < n; i++) {
minHeap.add(d[i]);
// if size of heap increases pop tht last element
if(minHeap.size()>k) {
minHeap.poll();
}
}
// print remaining element
//HERE IS THE PROBLEM I WANT IT IN " DECREASING ORDER "
// it gives me Increasing order
while(minHeap.size() > 0) {
System.out.print(minHeap.peek()+" ");
minHeap.poll();
}
System.out.println();
}// end of while
}// end of main
}// end of class
输入:
1
5 2
125787123
输出:
23787
# 1 楼答案
只需将代码替换为以下内容
在声明优先级队列时,您可以按相反顺序提供比较器
PriorityQueue newHeap=newpriorityqueue(minHeap.size(),比较器。反转顺序()强>
在这里,我创建了一个新堆,它将以reverseOrder存储所有现有元素,然后按原样执行所有现有操作
它给出了预期的答案
这对你有帮助
# 2 楼答案
您可以使用
Stream
打印结果: