33.丑数

import java.util.ArrayList;
public class Solution {
    public int GetUglyNumber_Solution(int index) {
        if(index<7){
            return index;
        }
        int p2=0,p3=0,p5=0,newNum=1;
        ArrayList<Integer> list=new ArrayList<>();
        list.add(newNum);
        while(list.size()<index){
            int m2=list.get(p2)*2;
            int m3=list.get(p3)*3;
            int m5=list.get(p5)*5;
            newNum=Math.min(m2,Math.min(m3,m5));
            list.add(newNum);
            if(newNum==m2) p2++;
            if(newNum==m3) p3++;
            if(newNum==m5) p5++;
        }
        return newNum;
    }
}