Super Ugly Number

一、问题描述

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.

二、思路

思路类似于关于求第N个丑数的另一道题目： Ugly Number II

三、代码

class Solution {
public:
    int nthSuperUglyNumber(int n,vector<int>& primes){
        int len = primes.size();
        vector<int> v(n,0);
        v[0] = 1;
        vector<int> c(len,0);
        vector<int> t(len,0);
        for(int i = 1; i < n; ++i){
            for(int j = 0; j < len; ++j){
                c[j] = v[t[j]] * primes[j];
            }
            int min_num = c[0];
            for(int k = 1; k < len; ++k){
                if(c[k] < min_num)
                    min_num = c[k];
            }
            v[i] = min_num;
            for(int m = 0; m < len; ++m){
                if(c[m] == min_num){
                    t[m]++;
                }
            }
        }
        return v[n - 1];
    }
};