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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.难度：medium
题目：写程序找出第 n 个超级丑数。超级丑数是正整数且其公因子由给定的素数组成。
思路：同丑数，三路指针换成一组指针用数组表示。
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];
}
}
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