Set correct starting position for high cursor (TheAlgorithms#646)

src/sorting/quick_sort.rs

@@ -3,22 +3,22 @@ use std::cmp::PartialOrd;
 pub fn partition<T: PartialOrd>(arr: &mut [T], lo: usize, hi: usize) -> usize {
  let pivot = hi;
  let mut i = lo;
- let mut j = hi;
+ let mut j = hi - 1;
 
  loop {
  while arr[i] < arr[pivot] {
  i += 1;
  }
- while j > 0 && arr[j - 1] > arr[pivot] {
+ while j > 0 && arr[j] > arr[pivot] {
  j -= 1;
  }
- if j == 0 || i >= j - 1 {
+ if j == 0 || i >= j {
  break;
- } else if arr[i] == arr[j - 1] {
+ } else if arr[i] == arr[j] {
  i += 1;
  j -= 1;
  } else {
- arr.swap(i, j - 1);
+ arr.swap(i, j);
  }
  }
  arr.swap(i, pivot);