102 lines
3.0 KiB
Java
102 lines
3.0 KiB
Java
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//中位数是有序列表中间的数。如果列表长度是偶数，中位数则是中间两个数的平均值。
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//
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// 例如，
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//
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// [2,3,4] 的中位数是 3
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//
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// [2,3] 的中位数是 (2 + 3) / 2 = 2.5
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//
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// 设计一个支持以下两种操作的数据结构：
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//
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//
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// void addNum(int num) - 从数据流中添加一个整数到数据结构中。
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// double findMedian() - 返回目前所有元素的中位数。
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//
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//
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// 示例：
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//
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// addNum(1)
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//addNum(2)
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//findMedian() -> 1.5
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//addNum(3)
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//findMedian() -> 2
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//
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// 进阶:
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//
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//
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// 如果数据流中所有整数都在 0 到 100 范围内，你将如何优化你的算法？
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// 如果数据流中 99% 的整数都在 0 到 100 范围内，你将如何优化你的算法？
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//
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// Related Topics 设计 双指针 数据流 排序 堆（优先队列）
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// 👍 449 👎 0
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package leetcode.editor.cn;
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import java.util.*;
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//295:数据流的中位数
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public class FindMedianFromDataStream {
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public static void main(String[] args) {
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//测试代码
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// Solution solution = new FindMedianFromDataStream().new Solution();
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MedianFinder medianFinder = null;
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List<String> list1 = Arrays.asList("MedianFinder", "addNum", "findMedian", "addNum", "findMedian", "addNum", "findMedian", "addNum", "findMedian", "addNum", "findMedian");
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List<Integer> list2 = Arrays.asList(null, -1, null, -2, null, -3, null, -4, null, -5, null);
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for (int i = 0; i < list1.size(); i++) {
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if ("MedianFinder".equals(list1.get(i))) {
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medianFinder = new FindMedianFromDataStream().new MedianFinder();
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} else if ("addNum".equals(list1.get(i))) {
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medianFinder.addNum(list2.get(i));
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} else {
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System.out.println(medianFinder.findMedian());
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}
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}
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}
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//力扣代码
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//leetcode submit region begin(Prohibit modification and deletion)
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class MedianFinder {
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/**
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* 当前大顶堆和小顶堆的元素个数之和
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*/
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private int count;
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private PriorityQueue<Integer> max;
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private PriorityQueue<Integer> minheap;
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/**
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* initialize your data structure here.
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*/
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public MedianFinder() {
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count = 0;
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max = new PriorityQueue<>((x, y) -> y - x);
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minheap = new PriorityQueue<>();
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}
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public void addNum(int num) {
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count += 1;
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max.offer(num);
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minheap.add(max.poll());
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if ((count & 1) != 0) {
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max.add(minheap.poll());
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}
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}
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public double findMedian() {
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if ((count & 1) == 0) {
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return (double) (max.peek() + minheap.peek()) / 2;
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} else {
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return (double) max.peek();
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}
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}
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}
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/**
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* Your MedianFinder object will be instantiated and called as such:
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* MedianFinder obj = new MedianFinder();
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* obj.addNum(num);
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* double param_2 = obj.findMedian();
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*/
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//leetcode submit region end(Prohibit modification and deletion)
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}
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