点击链接PAT甲级-AC全解汇总

题目：
Given any positive integer N, you are supposed to find all of its prime factors, and write them in the format N = p_​1​​ ​k_​1​​ ​​ ×p_​2​​ ​k_​2​​ ​​ ×⋯×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 = p_​1​​ ^k_​1​​ *p_​2​​ ^k_​2​​ *…*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
1

Sample Output:

97532468=2^2*11*17*101*1291
1

题意：
质因数分解

算法笔记的代码：

#include
#include
const int maxn=10000;
struct factor {
    int x,cnt=0;
} fac[10];
bool isprime(int n) {
    if(n<=1)
        return false;
    int sqr=(int) sqrt(n);
    for(int i=2; i<=sqr; i++) {
        if(n%i==0)
            return false;
    }
    return true;
}
int prime[maxn]= {0},num=0;

void find_prime() {
    for(int i=2; i<maxn; i++) {
        if(isprime(i))
            prime[num++]=i;
    }
}

int main() {
    find_prime();
    int n;
    int k=0;
    scanf("%d",&n);
    if(n==1)
        printf("1=1");
    else {
        printf("%d=",n);
        while(!isprime(n)&&n>1) {
            for(int i=0; i<num; i++) {
                if(n%prime[i]==0) {
                    fac[k].x=prime[i];
                    while(n%prime[i]==0) {
                        n/=prime[i];
                        fac[k].cnt++;
                    }
                    k++;
                }
                if(n==1)
                    break;
            }
        }
        if(n!=1) {
            fac[k].x=n;
            fac[k++].cnt=1;
        }
        for(int i=0; i<k; i++) {
            printf("%d",fac[i].x);
            if(fac[i].cnt>1) {
                printf("^%d",fac[i].cnt);
            }
            if(i<k-1)
                printf("*");
        }
    }

    return 0;
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64