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描述
Write a function to find the n-th super ugly number.
Super ugly numbers are positive numbers whose all prime factors are in the given prime list primes of size k. For example, [1, 2, 4, 7, 8, 13, 14, 16, 19, 26, 28, 32] is the sequence of the first 12 super ugly numbers given primes = [2, 7, 13, 19] of size 4.
Note:
- 1 is a super ugly number for any given primes.
- The given numbers in primes are in ascending order.
- 0 < k ≤ 100, 0 < n ≤ 1000000, 0 < primes[i] < 1000.
分析
这题是 Ugly Number II 的扩展。在"Ugly Number II"中，primes=[2,3,5]，这题中primes可以自由变化。
所以这题可以用"Ugly Number II"的思路解决。每次要从多个列表中选择最小的元素，我们可以维护一个大小为primes长度的小根堆。
