A - K进制下的大数

https://vjudge.net/contest/218366#problem/A

中间溢出，注意求模。

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cstring>
 4 #include<algorithm>
 5 #include<cstdlib>
 6 #include<cmath>
 7 #include<vector>
 8 #include<stack>
 9 #include<queue>
10 #define lson l, m, rt<<1
11 #define rson m+1, r, rt<<1|1
12 #define IO ios::sync_with_stdio(false);cin.tie(0);
13 #define INF 0x3f3f3f3f
14 #define MAXN 100010
15 const int MOD=1e9+7;
16 typedef __int64 ll;
17 using namespace std;
18 char s[MAXN];
19 ll a[MAXN],maxm;
20 int main()
21 {
22     IO;
23     while(cin >> s){
24         maxm = -INF ;
25         ll len = strlen(s);
26         for(int i = 0; i < len; i++){
27             if(s[i] >= '0'&&s[i] <= '9'){
28                 a[i] = s[i]-'0';
29                 maxm = max(maxm, a[i]);
30             }
31             else{
32                 a[i] = s[i]-'A'+10;
33                 maxm = max(maxm, a[i]);
34             }
35         }
36         ll flag=0, loc, r, sum;
37         ll beg = max((ll)2, maxm)+1;//起点必须加一 
38         for(int i = beg; i <= 36; i++){
39             r=1;sum=0;
40             for(int j = 0; j < len; j++){//中间溢出，求模的技巧 
41                 sum = (sum+a[len-1-j]*r%(i-1))%(i-1);
42                 r = r*i%(i-1);
43             }        
44             if(sum==0){
45                 flag=1;loc=i;
46                 break;
47             }
48         }
49         if(!flag) cout << "No Solution" << endl;
50         else cout << loc << endl;
51     }
52     return 0;
53 }

 

posted @ 2018-03-27 11:05  Surprisez  阅读(138)  评论(0)  编辑  收藏  举报