Ugly Number II

phlovexz

于 2016-06-21 21:31:20 发布

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分类专栏： LeetCode 文章标签： c语言

本文链接：https://blog.youkuaiyun.com/u013609078/article/details/51730304

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c++

class Solution {
public:
    int nthUglyNumber(int n) {
        if (n == 1) return 1;
        vector<int> idx(9, 0);
        vector<int> ugly(n, INT_MAX);
        ugly[0] = 1;
        for (int i = 1; i < n; ++i) {
            for (int j = 0; j < 9; ++j) {
                ugly[i] = min(ugly[i], primes[j] * ugly[idx[j]]);
            }
            for (int j = 0; j < 9; ++j) {
                while (primes[j] * ugly[idx[j]] <= ugly[i]) {
                    idx[j] ++;
                }
            }
        }
        return ugly.back();
    }
private:
    vector<int> primes{ 2, 3, 4, 5, 6, 8, 9, 10, 12 };
};