README.md

697. Degree of an Array

Given a non-empty array of non-negative integers nums, the degree of this array is defined as the maximum frequency of any one of its elements.

Your task is to find the smallest possible length of a (contiguous) subarray of nums, that has the same degree as nums.

Example 1:

Input: [1, 2, 2, 3, 1]
Output: 2
Explanation:
The input array has a degree of 2 because both elements 1 and 2 appear twice.
Of the subarrays that have the same degree:
[1, 2, 2, 3, 1], [1, 2, 2, 3], [2, 2, 3, 1], [1, 2, 2], [2, 2, 3], [2, 2]
The shortest length is 2. So return 2.

Example 2:

Input: [1,2,2,3,1,4,2]
Output: 6

Note:

• nums.length will be between 1 and 50,000.
• nums[i] will be an integer between 0 and 49,999.

Solutions (Rust)

1. HashMap

use std::collections::HashMap;

impl Solution {
    pub fn find_shortest_sub_array(nums: Vec<i32>) -> i32 {
        let mut cnt_left_len = HashMap::new();
        let mut degree = 0;

        for i in 0..nums.len() {
            let cll = cnt_left_len.entry(nums[i]).or_insert([0, i, 1]);
            cll[0] += 1;
            cll[2] = i - cll[1] + 1;
            degree = degree.max(cll[0])
        }

        cnt_left_len.values()
                    .filter(|arr| arr[0] == degree)
                    .map(|arr| arr[2])
                    .min()
                    .unwrap() as i32
    }
}