[Algorithm] 롤케이크 자르기

[hwangJi-dev]

https://school.programmers.co.kr/learn/courses/30/lessons/132265#

import Foundation

func solution(_ topping:[Int]) -> Int {
 var tops = Array(repeating: 0, count: topping.max()! + 1)
 
 for i in topping {
 tops[i] += 1
 }
 
 var pointer = 0
 var q1 = Set(topping).count
 var q2: Set<Int> = []
 var ans = 0
 
 while pointer <= topping.count - 1 {
 let ct = topping[pointer]
 tops[ct] -= 1
 
 if tops[ct] == 0 {
 q1 -= 1
 }
 
 q2.insert(ct)
 if q1 == q2.count {
 ans += 1
 }
 
 pointer += 1
 }
 
 return ans
}