// From the software distribution accompanying the textbook
// "A Practical Introduction to Data Structures and Algorithm Analysis,
// Third Edition (C++)" by Clifford A. Shaffer.
// Source code Copyright (C) 2007-2011 by Clifford A. Shaffer.

// Quicksort implementation and timing test driver
// Basic Quicksort version

#include "book.h"

// Include comparator functions
#include "compare.h"

// Simple findpivot: Pick middle value in array
template <typename E>
inline int findpivot(E A[], int i, int j)
  { return (i+j)/2; }

// Partition the array
template <typename E, typename Comp>
inline int partition(E A[], int l, int r, E& pivot) {
  do {             // Move the bounds inward until they meet
    while (Comp::prior(A[++l], pivot));  // Move l right and
    while ((l < r) && Comp::prior(pivot, A[--r])); // r left
    swap(A, l, r);              // Swap out-of-place values
  } while (l < r);              // Stop when they cross
  return l;      // Return first position in right partition
}

// qsort core function: Basic qsort
template <typename E, typename Comp>
void qsort(E A[], int i, int j) { // Quicksort
  if (j <= i) return; // Don't sort 0 or 1 element
  int pivotindex = findpivot(A, i, j);
  swap(A, pivotindex, j);    // Put pivot at end
  // k will be the first position in the right subarray
  int k = partition<E,Comp>(A, i-1, j, A[j]);
  swap(A, k, j);             // Put pivot in place
  qsort<E,Comp>(A, i, k-1);
  qsort<E,Comp>(A, k+1, j);
}

template <typename E, typename Comp>
void sort(E* array, int n) {
  qsort<E,Comp>(array, 0, n-1);
}

#include "sortmain.cpp"

int main(int argc, char** argv) {
  return sortmain<minintCompare>(argc, argv);
}