void InSert(int* a, int n)
{
for (int i = 1; i < n; i++)
{
int end = i - 1;
int tmp = a[i];
while (end >= 0)
{
if (tmp < a[end])
{
a[end + 1] = a[end];
end--;
}
else
{
break;
}
}
a[end + 1] = tmp;
}
}
void InsertSort(int* a, int n)
{
int gap = 3;
for (j=0;j<gap;j++)
{
for (int i = j; i < n-gap; i+=gap)
{
int end = i;
int tmp = a[i+gap];
while (end >= 0)
{
if (tmp < a[end])
{
a[end + gap] = a[end];
end-=gap;
}
else
{
break;
}
}
a[end + gap] = tmp;
}
}
}
void InsertSort(int* a, int n)
{
int gap = n;
int j = 0;
while (gap > 1)
{
gap = gap / 2;
for (j = 0; j < gap; j++)
{
for (int i = j; i < n - gap; i += gap)
{
int end = i;
int tmp = a[i + gap];
while (end >= 0)
{
if (tmp < a[end])
{
a[end + gap] = a[end];
end -= gap;
}
else
{
break;
}
}
a[end + gap] = tmp;
}
}
}
}
//这是两个点的移动
void SelectSort(int* a, int n)
{
int left = 0, right = n - 1;
while (left < right)
{
int mini = left, maxi = left;
for (int i = left + 1; i <= right; i++)
{
if (a[i] < a[mini])
{
mini = i;
}
if (a[i] > a[maxi])
{
maxi = i;
}
}
Swap(&a[left], &a[mini]);
// 如果left和maxi重叠，交换后修正一下
if (left == maxi)
{
maxi = mini;
}
Swap(&a[right], &a[maxi]);
++left;
--right;
}
}
堆排序
就是以层序的方式从下往上，从大到小的排。升序建大堆，降序建小堆。
// 左右子树都是大堆/小堆
void AdjustDown(int* a, int n, int parent)
{
int child = parent * 2 + 1;
while (child < n)
{
// 选出左右孩子中大的那一个
if (child + 1 < n && a[child + 1] > a[child])
{
++child;
}
if (a[child] > a[parent])
{
Swap(&a[child], &a[parent]);
parent = child;
child = parent * 2 + 1;
}
else
{
break;
}
}
}
void HeapSort(int* a, int n)
{
// 建堆 -- 向下调整建堆 -- O(N)
for (int i = (n - 1 - 1) / 2; i >= 0; --i)
{
AdjustDown(a, n, i);
}
// 自己先实现 -- O(N*logN)
int end = n - 1;
while (end > 0)
{
Swap(&a[end], &a[0]);
AdjustDown(a, end, 0);
--end;
}
}
冒泡排序
冒泡排序，好理解，教学意义重大。简单的来说就是从一端开始，两两交换，把小的换在前面去就OK了！
void BubbleSort(int* a, int n)
{
for (int j = 0; j < n; j++)
{
bool exchange = false;
for (int i = 1; i < n - j; i++)
{
if (a[i - 1] > a[i])
{
Swap(&a[i - 1], &a[i]);
exchange = true;
}
}
if (exchange == false)
{
break;
}
}
}
快速排序(快排）
快排有很多种方法，比如hoare法，挖坑法，前后指针法：
1.hoare法：
无言，如图所示
int GetMidNumi(int* a, int left, int right)
{
int mid = (left + right) / 2;
if (a[left] < a[mid])
{
if (a[mid] < a[right])
{
return mid;
}
else if (a[left] > a[right])
{
return left;
}
else
{
return right;
}
}
else // a[left] > a[mid]
{
if (a[mid] > a[right])
{
return mid;
}
else if (a[left] < a[right])
{
return left;
}
else
{
return right;
}
}
}
int PartSort1(int* a, int left, int right)
{
// 三数取中
int midi = GetMidNumi(a, left, right);
if (midi != left)
Swap(&a[midi], &a[left]);
int keyi = left;
while (left < right)
{
// 右边找小
while (left < right && a[right] >= a[keyi])
--right;
// 左边找大
while (left < right && a[left] <= a[keyi])
++left;
Swap(&a[left], &a[right]);
}
Swap(&a[keyi], &a[left]);
keyi = left;
return keyi;
}
挖坑法：
int GetMidNumi(int* a, int left, int right)
{
int mid = (left + right) / 2;
if (a[left] < a[mid])
{
if (a[mid] < a[right])
{
return mid;
}
else if (a[left] > a[right])
{
return left;
}
else
{
return right;
}
}
else // a[left] > a[mid]
{
if (a[mid] > a[right])
{
return mid;
}
else if (a[left] < a[right])
{
return left;
}
else
{
return right;
}
}
}
int PartSort2(int* a, int left, int right)
{
// 三数取中
int midi = GetMidNumi(a, left, right);
if (midi != left)
Swap(&a[midi], &a[left]);
// 21:10继续
int key = a[left];
int hole = left;
while (left < right)
{
// 右边找小
while (left < right && a[right] >= key)
--right;
a[hole] = a[right];
hole = right;
// 左边找大
while (left < right && a[left] <= key)
++left;
a[hole] = a[left];
hole = left;
}
a[hole] = key;
return hole;
}
前后指针法：
int GetMidNumi(int* a, int left, int right)
{
int mid = (left + right) / 2;
if (a[left] < a[mid])
{
if (a[mid] < a[right])
{
return mid;
}
else if (a[left] > a[right])
{
return left;
}
else
{
return right;
}
}
else // a[left] > a[mid]
{
if (a[mid] > a[right])
{
return mid;
}
else if (a[left] < a[right])
{
return left;
}
else
{
return right;
}
}
}
int PartSort3(int* a, int left, int right)
{
// 三数取中
int midi = GetMidNumi(a, left, right);
if (midi != left)
Swap(&a[midi], &a[left]);
int keyi = left;
int prev = left;
int cur = left + 1;
while (cur <= right)
{
if (a[cur] < a[keyi] && ++prev != cur)
Swap(&a[cur], &a[prev]);
++cur;
}
Swap(&a[prev], &a[keyi]);
keyi = prev;
return keyi;
}
归并排序（递归）：
int GetMidNumi(int* a, int left, int right)
{
int mid = (left + right) / 2;
if (a[left] < a[mid])
{
if (a[mid] < a[right])
{
return mid;
}
else if (a[left] > a[right])
{
return left;
}
else
{
return right;
}
}
else // a[left] > a[mid]
{
if (a[mid] > a[right])
{
return mid;
}
else if (a[left] < a[right])
{
return left;
}
else
{
return right;
}
}
}
int PartSort3(int* a, int left, int right)
{
// 三数取中
int midi = GetMidNumi(a, left, right);
if (midi != left)
Swap(&a[midi], &a[left]);
int keyi = left;
int prev = left;
int cur = left + 1;
while (cur <= right)
{
if (a[cur] < a[keyi] && ++prev != cur)
Swap(&a[cur], &a[prev]);
++cur;
}
Swap(&a[prev], &a[keyi]);
keyi = prev;
return keyi;
}
void QuickSort(int* a, int left, int right)
{
if (left >= right)
return;
int keyi = PartSort3(a, left, right);
QuickSort(a, left, keyi - 1);
QuickSort(a, keyi + 1, right);
}
