From 32c01a94729763b9411623bb47ceb4eeea948273 Mon Sep 17 00:00:00 2001
From: yi-ge <a@wyr.me>
Date: Sun, 17 Sep 2023 15:52:47 +0800
Subject: [PATCH] add: heap sort 3 (Heapify)

---
 src/sort/heap_sort.cpp       | 34 +++++++++++++++++++++++++++++++++-
 test/lib/lib_test.cpp        |  2 +-
 test/sort/heap_sort_test.cpp |  9 ++++++++-
 3 files changed, 42 insertions(+), 3 deletions(-)

diff --git a/src/sort/heap_sort.cpp b/src/sort/heap_sort.cpp
index 0baacc8..143ffdd 100644
--- a/src/sort/heap_sort.cpp
+++ b/src/sort/heap_sort.cpp
@@ -3,8 +3,40 @@
 #include <headers.hpp>
 #include <max_heap.hpp>
 
+template <typename T> void __shiftDown(T arr[], int n, int k) {
+  while (2 * k + 1 < n) {
+    int j = 2 * k + 1; // 在此轮循环中，arr[k]和arr[j]交换位置
+    if (j + 1 < n && arr[j + 1] > arr[j]) {
+      j += 1;
+    }
+    if (arr[k] >= arr[j]) {
+      break;
+    }
+    swap(arr[k], arr[j]);
+    k = j;
+  }
+}
+
+template <typename T> void heapSort(T arr[], int n) {
+  // heapify
+  // 从(最后一个元素的索引-1)/2开始
+  // 最后一个元素的索引 = n-1
+  for (int i = (n - 1 - 1) / 2; i >= 0; i--) {
+    __shiftDown(arr, n, i);
+  }
+
+  for (int i = n - 1; i > 0; i--) {
+    swap(arr[0], arr[i]);
+    __shiftDown(arr, i, 0);
+  }
+}
+
 class Solution {
 public:
+  vector<int> heapSort(vector<int> &nums) {
+    ::heapSort(&nums[0], nums.size());
+    return nums;
+  }
   /**
    * @brief 堆排序
    * nlogn
@@ -32,7 +64,7 @@ class Solution {
    * @param nums
    * @return vector<int>
    */
-  vector<int> heapSort(vector<int> &nums) {
+  vector<int> heapSort2(vector<int> &nums) {
     int n = nums.size();
     int arr[n];
     for (int i = 0; i < n; i++) {
diff --git a/test/lib/lib_test.cpp b/test/lib/lib_test.cpp
index d5b2a62..47f80f9 100644
--- a/test/lib/lib_test.cpp
+++ b/test/lib/lib_test.cpp
@@ -1,4 +1,4 @@
-// 执行编译时间：2023-09-17 14:49:28
+// 执行编译时间：2023-09-17 15:52:26
 #include <gtest/gtest.h>
 #include <lib.hpp>
 
diff --git a/test/sort/heap_sort_test.cpp b/test/sort/heap_sort_test.cpp
index 86ca888..c9e03f3 100644
--- a/test/sort/heap_sort_test.cpp
+++ b/test/sort/heap_sort_test.cpp
@@ -11,5 +11,12 @@ TEST(堆排序, heapSort1) {
   Solution solution;
   vector<int> nums = {2, 1, 3, 5, 4};
   vector<int> actionVec = {1, 2, 3, 4, 5};
-  EXPECT_THAT(solution.heapSort(nums), ::testing::ContainerEq(actionVec));
+  EXPECT_THAT(solution.heapSort1(nums), ::testing::ContainerEq(actionVec));
+}
+
+TEST(堆排序, heapSort2) {
+  Solution solution;
+  vector<int> nums = {2, 1, 3, 5, 4};
+  vector<int> actionVec = {1, 2, 3, 4, 5};
+  EXPECT_THAT(solution.heapSort2(nums), ::testing::ContainerEq(actionVec));
 }
\ No newline at end of file