【leetcode】313. Super Ugly Number【M】【14】

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.

Credits:

Special thanks to @dietpepsi for adding this problem and creating all test cases.

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申请一个长度为n的数组res，用于从小到大顺序存储n个丑数，数组中的首项为1，即第一个丑数为1

设置三个变量idx2、idx3、idx5存储下标，初始值都为0

找出数组res[idx2]*2、res[idx3]*3、res[idx5]*5的最小值，最小值即为下一个丑数，同时更新最小值对应的下标，如果多个数字同时为最小值，则它们的下标都要更新

找到第n个丑数时，循环结束

class Solution(object):
def nthSuperUglyNumber(self, n, primes):
res = [1]
ind = [0] * len(primes)

for i in xrange(n+1):
t = []

for j in xrange(len(primes)):
t += res[ind[j]] * primes[j],
minn = min(t)
for j in xrange(len(primes)):
if t[j] == minn:
ind[j] += 1

res += minn,
#print t,res

return res[n-1]