LeetCode 313 Super Ugly Number

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.

解法一：具体思路和LeetCode 264 Ugly Number II的解法二一样

public int nthSuperUglyNumber(int n, int[] primes) {
int[] nums = new int
;
nums[0] = 1;
int[] index = new int[primes.length];
int cout = 1;
while (cout < n) {
int minNum = Integer.MAX_VALUE;
for (int i = 0; i < primes.length; i++) {
minNum = Math.min(nums[index[i]] * primes[i], minNum);
}
for (int i = 0; i < primes.length; i++) {
if (nums[index[i]] * primes[i] == minNum) index[i]++;
}
nums[cout++] = minNum;
}
return nums[n - 1];
}

根据leetcode的提示，这个题目是可以使用heap的，可是对heap的操作又不熟悉，所以，这个算法暂时作罢。以后如果有更简洁的算法，再补上。

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