313. Super Ugly Number
摘要：
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 li...
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.
Example:
Input: n = 12, primes = [2,7,13,19] Output: 32 Explanation: [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 ≤ 106, 0 < primes[i] < 1000. The nth super ugly number is guaranteed to fit in a 32-bit signed integer.
難度：medium
題目：寫程式找出第n個超級醜數。超級醜數是正整數且其公因子由給定的素陣列成。
思路：同醜數，三路指標換成一組指標用陣列表示。
Runtime: 11 ms, faster than 97.31% of Java online submissions for Super Ugly Number.
Memory Usage: 34.2 MB, less than 82.00% of Java online submissions for Super Ugly Number.
class Solution {
public int nthSuperUglyNumber(int n, int[] primes) {
long[] ugly = new long[n];
ugly[0] = 1;
int[] p = new int[primes.length];
for (int i = 1; i < n; i++) {
long minVal = primes[0] * ugly[i - 1];
for (int j = 0; j < primes.length; j++) {
long num = ugly[p[j]] * primes[j];
if (num < minVal) {
minVal = num;
}
}
ugly[i] = minVal;
for (int j = 0; j < primes.length; j++) {
if (ugly[p[j]] * primes[j] == minVal) {
p[j]++;
}
}
}
return (int) ugly[n - 1];
}
}