剑指offer-丑数

public class Solution {
    public int GetUglyNumber_Solution(int index) {
        if(index <= 0){
            return 0;
        }
        //分别记录质因子2，3，5所计算到的位置。
        int i2 = 0;
        int i3 = 0;
        int i5 = 0;
        int[] arr = new int[index];
        arr[0] = 1;
        for(int i = 1;i < index;i++){
            int a = arr[i2]*2;
            int b = arr[i3]*3;
            int c = arr[i5]*5;
            while(a <= arr[i-1]){
                a = arr[++i2] * 2;
            }
            while(b <= arr[i-1]){
                b = arr[++i3] * 3;
            }
            while(c <= arr[i-1]){
                c = arr[++i5] * 5;
            }
            arr[i] = a>b?(b>c?c:b):(a>c?c:a);
        }
        return arr[index - 1];
    }
}

public class Solution {
    public int GetUglyNumber_Solution(int index) {
        if(index <= 0){
            return 0;
        }
        //分别记录质因子2，3，5所计算到的位置。
        int i2 = 0;
        int i3 = 0;
        int i5 = 0;
        int[] arr = new int[index];
        arr[0] = 1;
        for(int i = 1;i < index;i++){
            int a = arr[i2]*2;
            int b = arr[i3]*3;
            int c = arr[i5]*5;
            arr[i] = a>b?(b>c?c:b):(a>c?c:a);
            if(a == arr[i]){i2++;}
            if(b == arr[i]){i3++;}
            if(c == arr[i]){i5++;}
        }
        return arr[index - 1];
    }
}