Question Definition
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.
(4) The nth super ugly number is guaranteed to fit in a 32-bit signed integer.
Java Solution
public int nthSuperUglyNumber(int n, int[] primes) {
int size = primes.length;
int q[] = new int[n];
int idxes[] = new int[size];
int vals[] = new int[size];
q[0] = 1;
for (int i = 1; i < n; i++) {
for (int j = 0; j < size; j++) {
vals[j] = q[idxes[j]] * primes[j];
}
q[i] = findMin(vals);
for (int j = 0; j < size; j++) {
if (vals[j] == q[i]) {
idxes[j] += 1;
}
}
}
return q[n - 1];
}
public int findMin(int[] nums) {
int min = nums[0];
for (int i = 1; i < nums.length; i++) {
min = Math.min(min, nums[i]);
}
return min;
}
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