Leetcode:丑数2

class Solution {
public:
    
    long long ret =INT_MAX;
    vector<int> v = { 2,3,5 };
    void dfs(long long tar, int idx, long long last)
    {
        if (tar > last)
        {
            if (ret == last)
                ret = tar;
            else ret = min(ret, tar);
            return;
        }
        for (int i = idx; i < 3; i++)
        {
            tar *= v[i];
            dfs(tar, i, last);
            tar /= v[i];
        }
    }
    int nthUglyNumber(int n)
    {
        long long last = 1;
        for (int i = 2; i <= n; i++)
        {
            dfs(1, 0, last);
            last = ret;
        }
        return ret == INT_MAX? 1 : ret;
    }
};

自己的方法，不是最优解。