Given an array of integers arr, write a function that returns true if and only if the number of occurrences of each value in the array is unique.
Example 1:
Input: arr = [1,2,2,1,1,3] Output: true Explanation: The value 1 has 3 occurrences, 2 has 2 and 3 has 1. No two values have the same number of occurrences.
Example 2:
Input: arr = [1,2] Output: false
Example 3:
Input: arr = [-3,0,1,-3,1,1,1,-3,10,0] Output: true
Constraints:
1 <= arr.length <= 1000-1000 <= arr[i] <= 1000struct Solution;
use std::collections::HashMap;
use std::collections::HashSet;
impl Solution {
fn unique_occurrences(arr: Vec<i32>) -> bool {
let mut hm: HashMap<i32, i32> = HashMap::new();
for x in arr {
*hm.entry(x).or_default() += 1;
}
let mut hs = HashSet::new();
for x in hm.values() {
if !hs.insert(x) {
return false;
}
}
true
}
}
#[test]
fn test() {
let arr = vec![1, 2, 2, 1, 1, 3];
assert_eq!(Solution::unique_occurrences(arr), true);
let arr = vec![1, 2];
assert_eq!(Solution::unique_occurrences(arr), false);
let arr = vec![-3, 0, 1, -3, 1, 1, 1, -3, 10, 0];
assert_eq!(Solution::unique_occurrences(arr), true);
}