Write a program to find the nth 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) 1
is a super ugly number for any given primes
.
(2) The given numbers in primes
are in ascending order.
(3) 0 < k
≤ 100, 0 < n
≤ 106, 0 < primes[i]
< 1000.
新博客原文: leetcode-super-ugly-number
更多题解 https://www.hrwhisper.me/leetcode-algorithm-solution/
题意:
给定因子Primes , 让你求第n个super ugly number。
super ugly number定义为:整数,且因子全部都在primes中。 注意1为特殊的super ugly number。
思路:
和 leetcode Ugly Number II 思路一样,要使得super ugly number 不漏掉,那么用每个因子去乘第一个,当前因子乘积是最小后,乘以下一个…..以此类推。
Java 130ms
// http://www.hrwhisper.me/leetcode-super-ugly-number/
public class Solution {
public int nthSuperUglyNumber(int n, int[] primes) {
int[] ugly_number = new int[n];
ugly_number[0] = 1;
PriorityQueue q = new PriorityQueue();
for (int i = 0; i < primes.length; i++)
q.add(new Node(0, primes[i], primes[i]));
for (int i = 1; i < n; i++) {
Node cur = q.peek();
ugly_number[i] = cur.val;
do {
cur = q.poll();
cur.val = ugly_number[++cur.index] * cur.prime;
q.add(cur);
} while (!q.isEmpty() && q.peek().val == ugly_number[i]);
}
return ugly_number[n - 1];
}
}
class Node implements Comparable {
int index;
int val;
int prime;
Node(int index, int val, int prime) {
this.val = val;
this.index = index;
this.prime = prime;
}
public int compareTo(Node x) {
return this.val > x.val ? 1 : -1;
}
}
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