leetcode:数学：Super Ugly Number（313）

Write a program to find the nth super ugly number.

Super ugly numbers are positive numbers whose all prime factors are in the given prime list primes of size k. For example, [1, 2, 4, 7, 8, 13, 14, 16, 19, 26, 28, 32] is the sequence of the first 12 super ugly numbers given primes = [2, 7, 13, 19] of size 4.

Note:
(1) 1 is a super ugly number for any given primes.
(2) The given numbers in primes are in ascending order.
(3) 0 < k ≤ 100, 0 < n ≤ 106, 0 < primes[i] < 1000.

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class Solution {public:    int nthSuperUglyNumber(int n, vector<int>& primes) {        vector<int> res(1, 1), idx(primes.size(), 0);        while (res.size() < n) {            vector<int> tmp;            int mn = INT_MAX;            for (int i = 0; i < primes.size(); ++i) {                tmp.push_back(res[idx[i]] * primes[i]);            }            for (int i = 0; i < primes.size(); ++i) {                mn = min(mn, tmp[i]);            }            for (int i = 0; i < primes.size(); ++i) {                if (mn == tmp[i]) ++idx[i];            }            res.push_back(mn);        }        return res.back();    }};