void randomizedQuickSort(vectoru32& v, u32 p, u32 r) {
if ( p < r ) {
u32 q = randomizedPartition(v, p, r);
if (q != 0)
randomizedQuickSort(v, p, q - 1);
randomizedQuickSort(v, q + 1, r);
}
}
int selectKthOrder(int * arr, int start, int end, int k) {
if(arr == NULL || start > end || k < start || k > end) {
perror("args error");
return -1;
}
int pivot = randomizedPartition(arr, start, end);
if(pivot > k) return selectKthOrder(arr, start, pivot-1, k);
if(pivot < k) return selectKthOrder(arr, pivot+1, end, k);
return arr[pivot];
}
void quickSort(int * arr, int start, int end){
if(arr == NULL) {
perror("args error");
}
if(start < end){
int pivot = randomizedPartition(arr, start, end);
quickSort(arr, start, pivot - 1);
quickSort(arr, pivot + 1, end);
}
}
// select i-st largest number from A[p] to A[r]
Distance randomizedSelect(Distance* A, int p, int r, int i) {
if (p == r)
return A[p];
int q = randomizedPartition(A, p, r);
int k = q - p + 1;
if (i == k) // the pivot value is the answer
return A[q];
else if (i < k) // on the left
return randomizedSelect(A, p, q-1, i);
else // on the right
return randomizedSelect(A, q+1, r, i-k);
}
