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|
/// Quick sort a slice with a custom comparison function
///
/// # Arguments
/// * `arr` - The mutable slice to be sorted
/// * `inverse` - Sort direction: true for descending, false for ascending
/// * `compare` - Comparison function that returns -1, 0, or 1 indicating the relative order of two elements
pub fn quick_sort_with_cmp<T, F>(arr: &mut [T], inverse: bool, compare: F)
where
F: Fn(&T, &T) -> i32,
{
quick_sort_with_cmp_helper(arr, inverse, &compare);
}
/// Quick sort for types that implement the PartialOrd trait
///
/// # Arguments
/// * `arr` - The mutable slice to be sorted
/// * `inverse` - Sort direction: true for descending, false for ascending
pub fn quick_sort<T: PartialOrd>(arr: &mut [T], inverse: bool) {
quick_sort_with_cmp(arr, inverse, |a, b| {
if a < b {
-1
} else if a > b {
1
} else {
0
}
});
}
fn quick_sort_with_cmp_helper<T, F>(arr: &mut [T], inverse: bool, compare: &F)
where
F: Fn(&T, &T) -> i32,
{
if arr.len() <= 1 {
return;
}
let pivot_index = partition_with_cmp(arr, inverse, compare);
let (left, right) = arr.split_at_mut(pivot_index);
quick_sort_with_cmp_helper(left, inverse, compare);
quick_sort_with_cmp_helper(&mut right[1..], inverse, compare);
}
fn partition_with_cmp<T, F>(arr: &mut [T], inverse: bool, compare: &F) -> usize
where
F: Fn(&T, &T) -> i32,
{
let len = arr.len();
let pivot_index = len / 2;
arr.swap(pivot_index, len - 1);
let mut i = 0;
for j in 0..len - 1 {
let cmp_result = compare(&arr[j], &arr[len - 1]);
let should_swap = if inverse {
cmp_result > 0
} else {
cmp_result < 0
};
if should_swap {
arr.swap(i, j);
i += 1;
}
}
arr.swap(i, len - 1);
i
}
#[cfg(test)]
pub mod sort_test {
use crate::data_sort::{quick_sort, quick_sort_with_cmp};
#[test]
fn test_quick_sort_ascending() {
let mut arr = [3, 1, 4, 1, 5, 9, 2, 6];
quick_sort(&mut arr, false);
assert_eq!(arr, [1, 1, 2, 3, 4, 5, 6, 9]);
}
#[test]
fn test_quick_sort_descending() {
let mut arr = [3, 1, 4, 1, 5, 9, 2, 6];
quick_sort(&mut arr, true);
assert_eq!(arr, [9, 6, 5, 4, 3, 2, 1, 1]);
}
#[test]
fn test_quick_sort_single() {
let mut arr = [42];
quick_sort(&mut arr, false);
assert_eq!(arr, [42]);
}
#[test]
fn test_quick_sort_already_sorted() {
let mut arr = [1, 2, 3, 4, 5];
quick_sort(&mut arr, false);
assert_eq!(arr, [1, 2, 3, 4, 5]);
}
#[test]
fn test_quick_sort_with_cmp_by_count() {
#[derive(Debug, PartialEq)]
struct WordCount {
word: String,
count: usize,
}
let mut words = vec![
WordCount {
word: "apple".to_string(),
count: 3,
},
WordCount {
word: "banana".to_string(),
count: 1,
},
WordCount {
word: "cherry".to_string(),
count: 5,
},
WordCount {
word: "date".to_string(),
count: 2,
},
];
quick_sort_with_cmp(&mut words, false, |a, b| {
if a.count < b.count {
-1
} else if a.count > b.count {
1
} else {
0
}
});
assert_eq!(
words,
vec![
WordCount {
word: "banana".to_string(),
count: 1
},
WordCount {
word: "date".to_string(),
count: 2
},
WordCount {
word: "apple".to_string(),
count: 3
},
WordCount {
word: "cherry".to_string(),
count: 5
},
]
);
quick_sort_with_cmp(&mut words, true, |a, b| {
if a.count < b.count {
-1
} else if a.count > b.count {
1
} else {
0
}
});
assert_eq!(
words,
vec![
WordCount {
word: "cherry".to_string(),
count: 5
},
WordCount {
word: "apple".to_string(),
count: 3
},
WordCount {
word: "date".to_string(),
count: 2
},
WordCount {
word: "banana".to_string(),
count: 1
},
]
);
}
#[test]
fn test_quick_sort_with_cmp_by_first_letter() {
let mut words = vec!["zebra", "apple", "banana", "cherry", "date"];
quick_sort_with_cmp(&mut words, false, |a, b| {
let a_first = a.chars().next().unwrap();
let b_first = b.chars().next().unwrap();
if a_first < b_first {
-1
} else if a_first > b_first {
1
} else {
0
}
});
assert_eq!(words, vec!["apple", "banana", "cherry", "date", "zebra"]);
quick_sort_with_cmp(&mut words, true, |a, b| {
let a_first = a.chars().next().unwrap();
let b_first = b.chars().next().unwrap();
if a_first < b_first {
-1
} else if a_first > b_first {
1
} else {
0
}
});
assert_eq!(words, vec!["zebra", "date", "cherry", "banana", "apple"]);
}
}
|
