2024/9/19 Hot100 Heap 昨日堆

src/main/java/com/cool/hot100/heap/Num215.java

@@ -0,0 +1,68 @@
+package com.cool.hot100.heap;
+
+/**
+ * Created with IntelliJ IDEA.
+ *
+ * @Author: Cool
+ * @Date: 2024/09/19/11:11
+ * DayNumber 1
+ * Hard 2
+ * Level ?
+ */
+public class Num215 {
+    /**
+     * 桶排序
+     *
+     * @param nums
+     * @param k
+     * @return
+     */
+    public int findKthLargest(int[] nums, int k) {
+        int[] buckets = new int[20001];
+        for (int i = 0; i < nums.length; i++) {
+            buckets[nums[i] + 10000]++;
+        }
+        for (int i = 20000; i >= 0; i--) {
+            k = k - buckets[i];
+            if (k <= 0) {
+                return i - 10000;
+            }
+        }
+        return 0;
+    }
+
+    /**
+     * 快速排序，思路参考双路快速排序
+     *
+     * @param nums
+     * @param k
+     * @return
+     */
+    public int findKthLargest1(int[] nums, int k) {
+        return quickSearch(nums, 0, nums.length - 1, nums.length - k);
+    }
+
+    private int quickSearch(int[] nums, int left, int right, int k) {
+        if (left == right)
+            return nums[k];
+        int num = nums[left], i = left - 1, j = right + 1;
+        while (i < j) {
+            do
+                i++;
+            while (nums[i] < num);
+            do
+                j--;
+            while (nums[j] > num);
+            if (i < j) {
+                int temp = nums[i];
+                nums[i] = nums[j];
+                nums[j] = temp;
+            }
+        }
+        if (k <= j) {
+            return quickSearch(nums, left, j, k);
+        } else {
+            return quickSearch(nums, j + 1, right, k);
+        }
+    }
+}