题目描述
把只包含因子2、3和5的数称作丑数(Ugly Number)。例如6、8都是丑数,但14不是,因为它包含因子7。 习惯上我们把1当做是第一个丑数。求按从小到大的顺序的第N个丑数。
import java.util.ArrayList;
public class Solution {
public int GetUglyNumber_Solution(int index) {
if (index <= 0) return 0;
if (index == 1) return 1;
ArrayList<Integer> result = new ArrayList<Integer>();
result.add(1);
int t2 = 0, t3 = 0, t5 = 0;
for (int i = 1; i < index; i++) {
int min = Math.min(result.get(t2) * 2,Math.min(result.get(t3) * 3, result.get(t5) * 5));
result.add(min);
if (min == result.get(t2) * 2) t2++;
if (min == result.get(t3) * 3) t3++;
if (min == result.get(t5) * 5) t5++;
}
return result.get(index - 1);
}
}