[LeetCode] Problem 697 - Degree of an Array

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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

No.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.

No.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.

Code

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public int findShortestSubArray(int[] nums) {
    int result = Integer.MAX_VALUE;
    int degree = 0;
    Map<Integer, Integer> map = new HashMap<>();
    Map<Integer, Integer> index = new HashMap<>();

    for (int i = 0; i < nums.length; i++) {
        map.put(nums[i], map.getOrDefault(nums[i], 0) + 1);
        index.putIfAbsent(nums[i], i);
        int d = map.get(nums[i]);

        if (d > degree) {
            degree = d;
            result = i - index.get(nums[i]) + 1;
        } else if (d == degree)
            result = Math.min(result, i - index.get(nums[i]) + 1);
    }

    return result;
}