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Ugly numbers are positive numbers whose prime factors only include 2, 3, 5. For example, 6, 8 are ugly while 14 is not ugly since it includes another prime factor 7.
Note that 1 is typically treated as an ugly number.
public class Solution { public boolean isUgly(int num) { if(num == 0) return false; num = removeFactor(num, 2); num = removeFactor(num, 3); num = removeFactor(num, 5); return num == 1; } private int removeFactor(int num, int factor) { while(num%factor==0) { num = num/factor; } return num; } }
Write a program to find the n-th ugly number.
Ugly numbers are positive numbers whose prime factors only include 2, 3, 5. For example, 1, 2, 3, 4, 5, 6, 8, 9, 10, 12 is the sequence of the first 10 ugly numbers.
Note that 1 is typically treated as an ugly number.
Hint:
isUgly for every number until you reach the nth one. Most numbers are not ugly. Try to focus your effort on generating only the ugly ones.Hide Tags
public class Solution { public int nthUglyNumber(int n) { if(n==1) return 1; PriorityQueue<Long> q = new PriorityQueue(); q.add(1l); for(long i=1; i<n; i++) { long tmp = q.poll(); while(!q.isEmpty() && q.peek()==tmp) tmp = q.poll(); q.add(tmp*2); q.add(tmp*3); q.add(tmp*5); } return q.poll().intValue(); } }
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.
public class Solution { public int nthSuperUglyNumber(int n, int[] primes) { Arrays.sort(primes); if(n==1) return 1; PriorityQueue<Long> q = new PriorityQueue(); q.add(1l); for(long i=1; i<n; i++) { long tmp = q.poll(); while(!q.isEmpty() && q.peek()==tmp) tmp = q.poll(); for(Integer p: primes) { q.add(tmp*p); } } return q.poll().intValue(); } }
263. Ugly Number && 264. Ugly Number II && 313. Super Ugly Number
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原文地址：http://www.cnblogs.com/neweracoding/p/5659825.html
