LeetCode in Kotlin
2485. Find the Pivot Integer
Easy
Given a positive integer n, find the pivot integer x such that:
- The sum of all elements between
1andxinclusively equals the sum of all elements betweenxandninclusively.
Return the pivot integer x. If no such integer exists, return -1. It is guaranteed that there will be at most one pivot index for the given input.
Example 1:
Input: n = 8
Output: 6
Explanation: 6 is the pivot integer since: 1 + 2 + 3 + 4 + 5 + 6 = 6 + 7 + 8 = 21.
Example 2:
Input: n = 1
Output: 1
Explanation: 1 is the pivot integer since: 1 = 1.
Example 3:
Input: n = 4
Output: -1
Explanation: It can be proved that no such integer exist.
Constraints:
1 <= n <= 1000
Solution
class Solution {
fun pivotInteger(n: Int): Int {
if (n == 0 || n == 1) {
return n
}
var sum = 0
for (i in 1..n) {
sum += i
}
var ad = 0
for (i in 1..n) {
ad += i - 1
sum -= i
if (sum == ad) {
return i
}
}
return -1
}
}