825. Friends Of Appropriate Ages Medium

1/**
2 * [825] Friends Of Appropriate Ages
3 *
4 * There are n persons on a social media website. You are given an integer array ages where ages[i] is the age of the i^th person.
5 * A Person x will not send a friend request to a person y (x != y) if any of the following conditions is true:
6 * 
7 * 	age[y] <= 0.5 * age[x] + 7
8 * 	age[y] > age[x]
9 * 	age[y] > 100 &amp;&amp; age[x] < 100
10 * 
11 * Otherwise, x will send a friend request to y.
12 * Note that if x sends a request to y, y will not necessarily send a request to x. Also, a person will not send a friend request to themself.
13 * Return the total number of friend requests made.
14 *  
15 * Example 1:
16 * 
17 * Input: ages = [16,16]
18 * Output: 2
19 * Explanation: 2 people friend request each other.
20 * 
21 * Example 2:
22 * 
23 * Input: ages = [16,17,18]
24 * Output: 2
25 * Explanation: Friend requests are made 17 -> 16, 18 -> 17.
26 * 
27 * Example 3:
28 * 
29 * Input: ages = [20,30,100,110,120]
30 * Output: 3
31 * Explanation: Friend requests are made 110 -> 100, 120 -> 110, 120 -> 100.
32 * 
33 *  
34 * Constraints:
35 * 
36 * 	n == ages.length
37 * 	1 <= n <= 2 * 10^4
38 * 	1 <= ages[i] <= 120
39 * 
40 */
41pub struct Solution {}
42
43// problem: https://leetcode.com/problems/friends-of-appropriate-ages/
44// discuss: https://leetcode.com/problems/friends-of-appropriate-ages/discuss/?currentPage=1&orderBy=most_votes&query=
45
46// submission codes start here
47
48impl Solution {
49    pub fn num_friend_requests(ages: Vec<i32>) -> i32 {
50        0
51    }
52}
53
54// submission codes end
55
56#[cfg(test)]
57mod tests {
58    use super::*;
59
60    #[test]
61    fn test_825() {
62    }
63}
64