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leetcode 0313

admin 11月 13, 2020 0

Desicription

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.

Example:

Input: n = 12, primes = [2,7,13,19]
Output: 32 
Explanation: [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 is a super ugly number for any given primes.
The given numbers in primes are in ascending order.
0 < k ≤ 100, 0 < n ≤ 106, 0 < primes[i] < 1000.
The nth super ugly number is guaranteed to fit in a 32-bit signed integer.

Solution

class  {
public:
    int nthSuperUglyNumber(int n, std::vector<int>& primes) {
        auto index = std::vector<int>(primes.size(), 0);
        auto uglys = std::vector<int>(n, INT_MAX);
        uglys[0] = 1;

        for(auto& ugly : uglys) {
            for(int i = 0; i < index.size(); i++) {
                ugly = std::min(ugly, uglys[index[i]] * primes[i]);
            }
            for(int i = 0; i < index.size(); i++) {
                if(ugly == uglys[index[i]] * primes[i]) {
                    index[i]++;
                }
            }
        }

        return uglys[uglys.size() - 1];
    }
};