POJ 1142 Smith Numbers（分治法+质因数分解）

 1 #include <iostream>  
 2 #include <cstring>  
 3 #include <algorithm>   
 4 #include <vector>
 5 #include <queue>
 6 #include <cmath>
 7 using namespace std;
 8 
 9 int n;
10 
11 int cacl(int x)
12 {
13     int sum = 0;
14     while (x)
15     {
16         sum += x % 10;
17         x /= 10;
18     }
19     return sum;
20 }
21 
22 bool isprime(int x)
23 {
24     int m = sqrt(x + 0.5);
25     for (int i = 2; i <= m; i++)
26     {
27         if (x%i == 0)  return false;
28     }
29     return true;
30 }
31 
32 int solve(int x)
33 {
34     if (isprime(x))
35         return cacl(x);
36     else
37     {
38         int m = sqrt(x + 0.5);
39         for (int i = m; i >1;i--)
40         if (x%i == 0)
41             return solve(i) + solve(x / i);
42     }
43 }
44 
45 int main()
46 {
47     //freopen("D:\\input.txt", "r", stdin);
48     while (~scanf("%d", &n) && n)
49     {
50         for (int i = n + 1;; i++)
51         {
52             if (!isprime(i) && cacl(i) == solve(i))
53             {
54                 printf("%d\n", i);
55                 break;
56             }
57         }
58     }
59     return 0;
60 }