[LeetCode] 2148. Count Elements With Strictly Smaller and Greater Elements - 문제풀이

Description

주어진 정수 배열에서, num으로 표시되는 요소 수가 더 적거나 더 많은 모든 요소를 반환합니다. Given an integer array nums, return the number of elements that have both a strictly smaller and a strictly greater element appear in nums.

Example 1:

Input: nums = [11,7,2,15]
Output: 2
Explanation: The element 7 has the element 2 strictly smaller than it and the element 11 strictly greater than it.
Element 11 has element 7 strictly smaller than it and element 15 strictly greater than it.
In total there are 2 elements having both a strictly smaller and a strictly greater element appear innums.

Example 2:

Input: nums = [-3,3,3,90]
Output: 2
Explanation: The element 3 has the element -3 strictly smaller than it and the element 90 strictly greater than it.
Since there are two elements with the value 3, in total there are 2 elements having both a strictly smaller and a strictly greater element appear innums.

Constraints:

• 1 <= nums.length <= 100
• 105 <= nums[i] <= 105

Solution 1. Sort

public int countElements(int[] nums) {
    int len = nums.length;
    Arrays.sort(nums);
    int cnt = 0;
    int dupCnt = 0;
    for (int i = 1; i < len-1; i++) {
        if(nums[i] == nums[i+1]){
            nums[i] = nums[i-1];
            dupCnt++;
        }else{
            if(nums[i] > nums[i-1] && nums[i] <  nums[i+1]){
                cnt = cnt + dupCnt + 1;
            }
            dupCnt = 0;
        }
    }
    return cnt;
}

배열을 정렬 한 뒤 중복값일 경우는 더 작은 값으로 변경해주고 아닐경우 앞뒤 요소를 비교해서 앞으요소보다는 크고 뒤의 요소보다는 작을 경우 cnt를 추가해 반복하며 반환해 줍니다.

Reference

https://leetcode.com/problems/count-elements-with-strictly-smaller-and-greater-elements/