丑数

public int GetUglyNumber_Solution(int index) {

    if(index < 7)
        return index;
    int[] result = new int[index];
    result[0] = 1;
    int index2 = 0,index3 = 0,index5 = 0;
    for(int i = 1;i < index;i++){
        result[i] = Math.min(Math.min(2*result[index2],3*result[index3]),5*result[index5]);
        if(result[i] == result[index2]*2)
            index2++;
        if(result[i] == result[index3]*3)
            index3++;
        if(result[i] == result[index5]*5)
            index5++;

    }
    return result[index-1];
}