- Difficulty: Medium
- Tags: LeetCode, Medium, leetcode-3185, Hash Table, O(n + 24), O(24), Freq Table, Array, Counting
Problem
Given an integer array hours representing times in hours, return an integer denoting the number of pairs i, j where i < j and hours[i] + hours[j] forms a complete day.
A complete day is defined as a time duration that is an exact multiple of 24 hours.
For example, 1 day is 24 hours, 2 days is 48 hours, 3 days is 72 hours, and so on.
Example 1:
Input: hours = [12,12,30,24,24]
Output: 2
Explanation: The pairs of indices that form a complete day are (0, 1) and (3, 4).
Example 2:
Input: hours = [72,48,24,3]
Output: 3
Explanation: The pairs of indices that form a complete day are (0, 1), (0, 2), and (1, 2).
Constraints:
1 <= hours.length <= 5 * 1051 <= hours[i] <= 109