Leetcode

697. Degree of an Array

by hooni posted May 05, 2020
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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 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.

  • class Solution {
        public int findShortestSubArray(int[] nums) {
            Map<Integer, Integer> hmap = new HashMap<>();
            
            int degree = -1;
            //int number = nums[0];
            
            for(int num : nums){
                int count = hmap.getOrDefault(num, 0) + 1;
                if(degree < count){
                    degree = count;
                    //number = num;
                }
                hmap.put(num, count);
            }
            
            int minVal = Integer.MAX_VALUE;
            
            for(Map.Entry<Integer, Integer> item : hmap.entrySet()){
                if(item.getValue() == degree){
                    int number = item.getKey();
                    int left = -1;
                    int right = -1;
                    int len = nums.length;
                    for(int i=0; i<len; i++){
                        if(nums[i] == number && left == -1){
                            left = i;
                        }
    
                        if(nums[len-1-i] == number && right == -1){
                            right = len - 1 - i;
                        }
                    }
    
                    len = right < left ? 0 : right - left + 1;
                    if(minVal > len){
                        minVal = len;
                    }
                }
            }
            
            return minVal;
        }
    }


    [문제] https://leetcode.com/problems/degree-of-an-array/