题解 | #丑数# 这题有点意思

class Solution {
public:
    int GetUglyNumber_Solution(int index) {
        if (index <= 6) {
            return index;
        }
        int i2 = 0, i3 = 0, i5 = 0;
        vector<int>res(index, 0);
        res[0] = 1;
        for (int i = 1; i < index; i++) {
            res[i] = min(res[i2]*2, min(res[i3] *3, res[i5] *5));
            if (res[i] == res[i2] * 2) {
                i2++;
            }
            if (res[i] == res[i3] * 3) {
                i3++;
            }
            if (res[i] == res[i5] * 5) {
                i5++;
            }
        }
        return res[index-1];
    }
};