[leetcode]313. Super Ugly Number

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Analysis

missing—— [每天刷题并不难0.0]

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.

Explanation:

This problem is an extenssion of “ugly number” and “ugly number 2”. An new ugly number is previous ugly number multiply the factor in primes, and we take the minmum result as our newly ugly number.

Implement

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