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FindKthMaxNum.cpp
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79 lines (71 loc) · 1.1 KB
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#include <iostream.h>
void swap(int &a, int &b)
{
int temp = a;
a = b;
b = temp;
}
int Partion(int a[], int l, int r)
{
while (l < r)
{
while(l < r && a[l] < a[r])l++;
if (l < r)
{
swap(a[l], a[r]);
}
while(l < r && a[r] > a[l])r--;
if (l < r)
{
swap(a[l], a[r]);
}
}
return l;
}
void QuickSort(int a[], int l, int r)
{
if (l >= r)
{
return;
}
int pivot = Partion(a, l, r);
QuickSort(a, l, pivot - 1);
QuickSort(a, pivot + 1, r);
}
void Display(int a[], int n)
{
for (int i = 0; i < n; i++)
{
cout<<a[i]<<" ";
}
cout<<endl;
}
int FindKthMaxNum(int a[], int l, int r, int kth)
{
int pivot = Partion(a, l, r);
if (kth < pivot)
{
return FindKthMaxNum(a, l, pivot - 1, kth);
}
else if (kth == pivot)
{
return pivot;
}
else
{
return FindKthMaxNum(a, pivot+1, r, kth);
}
}
int main()
{
int a[10] = {0, 2, 1, 3, 4, 5, 6, 17, 9, 8};
int n = sizeof(a) / sizeof(int);
int kth, index;
//QuickSort(a, 0, n -1);
//cout<<"QuickSort:";
//Display(a, n);
kth = 10;
index = FindKthMaxNum(a, 0, n-1, kth);//indexΪkth
cout<<"KthMaxNum:"<<a[index-1]<<endl;
return 0;
}