PAT甲级 1059. Prime Factors (25)

题目：

Given any positive integer N, you are supposed to find all of its prime factors, and write them in the format N = p₁^k₁ * p₂^k₂ *…*p_m^k_m.

Input Specification:

Each input file contains one test case which gives a positive integer N in the range of long int.

Output Specification:

Factor N in the format N = p₁^k₁ * p₂^k₂ *…*p_m^k_m, where p_i's are prime factors of N in increasing order, and the exponent k_i is the number of p_i -- hence when there is only one p_i, k_i is 1 and must NOT be printed out.

Sample Input:

97532468

Sample Output:

97532468=2^2*11*17*101*1291

思路：

1.先构建质数表，根据N的大小，把1~sqrt(N)之间的质数找出来；

2.根据质数表，从小到大把N的因子找出，这里利用map比较好做；

3.注意N=1的情况

代码：

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