（劍指offer）醜數，只包含因子2、3和5的數稱作醜數

題目：按從小到大的順序輸出前n個醜數，習慣上把1當做第一個醜數；

代碼如下：

public class UglyNum {

    public static void main(String[] args) {
        // 要輸出的醜數個數
        int des = 1500;
        // 結果數組
        int[] result = new int[des];
        result = GetUglyNumber_Solution(des);
        int count = 0;
        for (int i = 0; i < result.length; i++) {
            System.out.print(result[i] + " ");
            count++;
            if (count % 10 == 0) {
                System.out.println();
            }
        }
    }

    public static int[] GetUglyNumber_Solution(int index) {
        if (index <= 0) {
            return null;
        }
        int[] uglyNum = new int[index];
        uglyNum[0] = 1;
        int nextUglyIdex = 1;

        int multiply2 = 0;
        int multiply3 = 0;
        int multiply5 = 0;

        while (nextUglyIdex < index) {
            int minUgly = Math.min(uglyNum[multiply2] * 2, 
                    Math.min(uglyNum[multiply3] * 3, uglyNum[multiply5] * 5));
            uglyNum[nextUglyIdex] = minUgly;
            while (uglyNum[multiply2] * 2 <= uglyNum[nextUglyIdex]) {
                multiply2++;
            }
            while (uglyNum[multiply3] * 3 <= uglyNum[nextUglyIdex]) {
                multiply3++;
            }
            while (uglyNum[multiply5] * 5 <= uglyNum[nextUglyIdex]) {
                multiply5++;
            }
            nextUglyIdex++;
        }

        return uglyNum;
    }
}

---

輸出結果：