leetcode (堆->simple)703,1046,前k大/小数
作者:互联网
703
第K大
class KthLargest { private PriorityQueue<Integer> heap ; private int k; public KthLargest(int k, int[] nums) { heap = new PriorityQueue<>(k,(k1,k2)->k1.compareTo(k2)); this.k = k; for (int i = 0; i < nums.length; i++) { if (i < k){ heap.add(nums[i]); }else { if (nums[i] >= heap.peek()){ heap.poll(); heap.add(nums[i]); } } } } public int add(int val) { if (heap.size() < k){ heap.add(val); } else if (val >= heap.peek()){ heap.poll(); heap.add(val); } return heap.peek(); } } /** * Your KthLargest object will be instantiated and called as such: * KthLargest obj = new KthLargest(k, nums); * int param_1 = obj.add(val); */
1046
也是用堆的特性来做
PriorityQueue<Integer> heap = new PriorityQueue<>((k1,k2)->k2.compareTo(k1)); for (int i = 0; i < stones.length; i++) { heap.offer(stones[i]); } while (heap.size() > 1){ Integer x1 = heap.poll(); Integer x2 = heap.poll(); if (x1 != x2){ heap.offer(Math.abs(x1-x2)); } } if (heap.isEmpty()){ return 0; } return heap.poll();
前大/小K 个数
public static int[] getLeastNumbers(int[] arr,int k) { if (k ==0 || arr.length == 0){ return new int[0]; } PriorityQueue<Integer> heap = new PriorityQueue<>((k1,k2)->k2.compareTo(k1)); for (int i = 0; i < arr.length; i++) { if (i < k){ heap.offer(arr[i]); }else { if (arr[i] < heap.peek()){ heap.poll(); heap.offer(arr[i]); } } } int size = heap.size(),ks = 0; int[] result = new int[size]; while (ks<size){ result[ks++] = heap.poll(); } return result; }
标签:1046,k2,simple,k1,int,add,heap,poll,leetcode 来源: https://www.cnblogs.com/hetutu-5238/p/14345189.html