leetcode 264: Ugly Number II

Posted 2020-09-30 mfmdaoyou

Ugly Number II

Total Accepted: 2920 Total Submissions: 15174

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.

[思路]

[CODE]

public class Solution {
    public int nthUglyNumber(int n) {
        int u = 0;
        List<Integer> l1 = new LinkedList<Integer>();
        List<Integer> l2 = new LinkedList<Integer>();
        List<Integer> l3 = new LinkedList<Integer>();
        l1.add(1);
        l2.add(1);
        l3.add(1);
        
        for(int i=0; i<n; i++) {
            u = Math.min( Math.min(l1.get(0), l2.get(0)), l3.get(0));
            
            if(l1.get(0) == u) l1.remove(0);
            if(l2.get(0) == u) l2.remove(0);
            if(l3.get(0) == u) l3.remove(0);
            
            l1.add(u*2);
            l2.add(u*3);
            l3.add(u*5);
        }
        return u;
    }
}