Friends of appropriate ages:
There are n persons on a social media website. You are given an integer array ages where ages[i] is the age of the ith person.
A Person x will not send a friend request to a person y (x != y) if any of the following conditions is true:
• age[y] <= 0.5 * age[x] + 7
• age[y] > age[x]
• age[y] > 100 && age[x] < 100
Otherwise, x will send a friend request to y.
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.
Return the total number of friend requests made.
Example 1:
Input: ages = [16,16]
Output: 2
Explanation: 2 people friend request each other.
Example 2:
Input: ages = [16,17,18]
Output: 2
Explanation: Friend requests are made 17 -> 16, 18 -> 17.
Example 3:
Input: ages = [20,30,100,110,120]
Output: 3
Explanation: Friend requests are made 110 -> 100, 120 -> 110, 120 -> 100.
Constraints:
• n == ages.length
• 1 <= n <= 2 * 104
• 1 <= ages[i] <= 120
class Solution {
public int numFriendRequests(int[] ages) {
int[][] requests = new int[ages.length][ages.length];
for (int i = 0; i < ages.length; i++) {
for (int j = 0; j < ages.length; j++){
requests[i][j] = 0;
}
}
int sum = 0;
for (int i = 0; i < ages.length; i++) {
for (int j = 0; j < ages.length; j++){
if (i == j) continue;
if (ages[j] <= 0.5 * ages[i] + 7) continue;
if (ages[j] > ages[i]) continue;
if (ages[j] > 100 && ages[i] < 100) continue;
requests[i][j] = 1;
sum += 1;
}
}
return sum;
}
}
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