Function count_values 

pub fn count_values<T>(collection: &[T]) -> HashMap<T, usize>
where
    T: Hash + Eq + Clone,

Counts the number of occurrences of each value in a collection.

This function iterates over a slice of items and returns a HashMap where each key is a unique item from the collection, and the corresponding value is the number of times that item appears.

Time Complexity: O(n), where n is the number of elements in the collection.

Arguments

• collection - A slice of items to be counted.

Type Parameters

• T - The type of elements in the input collection. Must implement Hash, Eq, and Clone.

Returns

• HashMap<T, usize> - A map where keys are unique items from the collection and values are their counts.

Examples

use lowdash::count_values;
use std::collections::HashMap;

let numbers = vec![1, 2, 2, 3, 4, 3, 5];
let result = count_values(&numbers);
let mut expected = HashMap::new();
expected.insert(1, 1);
expected.insert(2, 2);
expected.insert(3, 2);
expected.insert(4, 1);
expected.insert(5, 1);
assert_eq!(result, expected);

use lowdash::count_values;
use std::collections::HashMap;

#[derive(Debug, PartialEq, Eq, Hash, Clone)]
struct Person {
    name: String,
    age: u32,
}

let people = vec![
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Bob".to_string(), age: 30 },
    Person { name: "Alice".to_string(), age: 25 },
    Person { name: "Carol".to_string(), age: 35 },
];

let result = count_values(&people);
let mut expected = HashMap::new();
expected.insert(
    Person { name: "Alice".to_string(), age: 25 },
    2
);
expected.insert(
    Person { name: "Bob".to_string(), age: 30 },
    1
);
expected.insert(
    Person { name: "Carol".to_string(), age: 35 },
    1
);
assert_eq!(result, expected);