UVA - 1644 - Prime Gap（找相邻素数差值）

直接打表素数后查找即可。

 

 1 #include<cstdio>  
 2 #include<cstring>  
 3 #include<cctype>  
 4 #include<cstdlib>  
 5 #include<cmath>  
 6 #include<iostream>  
 7 #include<sstream>  
 8 #include<iterator>  
 9 #include<algorithm>  
10 #include<string>  
11 #include<vector>  
12 #include<set>  
13 #include<map>  
14 #include<queue>  
15 #include<stack>  
16 #include<list>  
17 #include<ctime>  
18 #define Memset(x) memset(x, 0, sizeof(x))  
19 #define all(x) x.begin(), x.end()  
20 const int E = 2000000 + 10;  
21 const double EPS = 1e-6;  
22 using namespace std;  
23   
24 typedef unsigned long long llu;  
25 vector<int> prime;  
26 int pri[E];  
27   
28 void dabiao(){  
29     pri[0] = 1, pri[1] = 1, pri[2] = 0;  
30     int len = 0;  
31     for(int i = 2; i < E; i++){  
32         if(len > 100000)  break;  
33         if(!pri[i]){  
34             prime.push_back(i);  len++;  
35             for(int j = i * 2; j < E; j += i)  
36                 pri[j] = 1;  
37         }  
38     }  
39 }  
40   
41 int main(){  
42     Memset(pri);  
43     dabiao();  
44     int n;  
45     while(scanf("%d", &n) == 1 && n){  
46         if(!pri[n])  {printf("0\n");  continue;}  
47         vector<int>::iterator temp = upper_bound(all(prime), n);  
48         printf("%d\n", *temp - *(temp - 1));  
49     }  
50     return 0;  
51 }

 

posted @ 2016-10-25 10:31  TianTengtt  阅读(235)  评论(0)    收藏  举报