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[cpp] Stick with swap #1474

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Aug 6, 2024
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[cpp] Stick with swap #1474

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a610a42
[cpp] Stick with swap
ZhongYuuu Aug 1, 2024
09e70e1
[cpp] Stick with swap
ZhongYuuu Aug 1, 2024
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53 changes: 16 additions & 37 deletions codes/cpp/chapter_sorting/quick_sort.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -9,26 +9,19 @@
/* 快速排序类 */
class QuickSort {
private:
/* 元素交换 */
static void swap(vector<int> &nums, int i, int j) {
int tmp = nums[i];
nums[i] = nums[j];
nums[j] = tmp;
}

/* 哨兵划分 */
static int partition(vector<int> &nums, int left, int right) {
// 以 nums[left] 为基准数
int i = left, j = right;
while (i < j) {
while (i < j && nums[j] >= nums[left])
j--; // 从右向左找首个小于基准数的元素
j--; // 从右向左找首个小于基准数的元素
while (i < j && nums[i] <= nums[left])
i++; // 从左向右找首个大于基准数的元素
swap(nums, i, j); // 交换这两个元素
i++; // 从左向右找首个大于基准数的元素
swap(nums[i], nums[j]); // 交换这两个元素
}
swap(nums, i, left); // 将基准数交换至两子数组的分界线
return i; // 返回基准数的索引
swap(nums[i], nums[left]); // 将基准数交换至两子数组的分界线
return i; // 返回基准数的索引
}

public:
Expand All @@ -48,13 +41,6 @@ class QuickSort {
/* 快速排序类（中位基准数优化） */
class QuickSortMedian {
private:
/* 元素交换 */
static void swap(vector<int> &nums, int i, int j) {
int tmp = nums[i];
nums[i] = nums[j];
nums[j] = tmp;
}

/* 选取三个候选元素的中位数 */
static int medianThree(vector<int> &nums, int left, int mid, int right) {
int l = nums[left], m = nums[mid], r = nums[right];
Expand All @@ -70,18 +56,18 @@ class QuickSortMedian {
// 选取三个候选元素的中位数
int med = medianThree(nums, left, (left + right) / 2, right);
// 将中位数交换至数组最左端
swap(nums, left, med);
swap(nums[left], nums[med]);
// 以 nums[left] 为基准数
int i = left, j = right;
while (i < j) {
while (i < j && nums[j] >= nums[left])
j--; // 从右向左找首个小于基准数的元素
j--; // 从右向左找首个小于基准数的元素
while (i < j && nums[i] <= nums[left])
i++; // 从左向右找首个大于基准数的元素
swap(nums, i, j); // 交换这两个元素
i++; // 从左向右找首个大于基准数的元素
swap(nums[i], nums[j]); // 交换这两个元素
}
swap(nums, i, left); // 将基准数交换至两子数组的分界线
return i; // 返回基准数的索引
swap(nums[i], nums[left]); // 将基准数交换至两子数组的分界线
return i; // 返回基准数的索引
}

public:
Expand All @@ -101,26 +87,19 @@ class QuickSortMedian {
/* 快速排序类（尾递归优化） */
class QuickSortTailCall {
private:
/* 元素交换 */
static void swap(vector<int> &nums, int i, int j) {
int tmp = nums[i];
nums[i] = nums[j];
nums[j] = tmp;
}

/* 哨兵划分 */
static int partition(vector<int> &nums, int left, int right) {
// 以 nums[left] 为基准数
int i = left, j = right;
while (i < j) {
while (i < j && nums[j] >= nums[left])
j--; // 从右向左找首个小于基准数的元素
j--; // 从右向左找首个小于基准数的元素
while (i < j && nums[i] <= nums[left])
i++; // 从左向右找首个大于基准数的元素
swap(nums, i, j); // 交换这两个元素
i++; // 从左向右找首个大于基准数的元素
swap(nums[i], nums[j]); // 交换这两个元素
}
swap(nums, i, left); // 将基准数交换至两子数组的分界线
return i; // 返回基准数的索引
swap(nums[i], nums[left]); // 将基准数交换至两子数组的分界线
return i; // 返回基准数的索引
}

public:
Expand Down