UVa 524 Prime Ring Problem (例题7-4)
2016-09-20 00:17
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这道题。。意思是比较明确的 但是自己写的时候在循环后面加了一个分号 导致数次不过。。妈的智障。。
题目来源:https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&category=&problem=465
思路:递归调用 判断是否用过并且是否素数
代码:
#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
int n,isp[50],A[50],yes[50],cnt = 0;
void tisp()
{
isp[2] = 1;
for(int i = 2;i<50;i++)
{
for(int j = 2;j<i;j++)
{
if(i%j==0)
{
isp[i] = 0;
break;
}
else isp[i] = 1;
}
}
}
void dfs(int cur)
{
if(cur == n&& isp[A[0]+A[n-1]])
{
for(int i = 0;i<n-1;i++)
cout<<A[i]<<" ";
cout<<A[n-1]<<endl;
}
else for(int i = 2;i<=n;i++)
{
if( !yes[i] && isp[i+A[cur-1]] )
{
A[cur] = i;
yes[i]=1;
dfs(cur+1);
yes[i] = 0;
}
}
}
int main()
{
memset(A,0,sizeof(A));
memset(isp,0,sizeof(isp));
memset(yes,0,sizeof(yes));
tisp();
A[0] = 1;
while(cin>>n)
{
if(cnt>0) cout<<endl;
cnt++;
cout<<"Case "<<cnt<<":"<<endl;
dfs(1);
}
return 0;
}
题目来源:https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&category=&problem=465
思路:递归调用 判断是否用过并且是否素数
代码:
#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
int n,isp[50],A[50],yes[50],cnt = 0;
void tisp()
{
isp[2] = 1;
for(int i = 2;i<50;i++)
{
for(int j = 2;j<i;j++)
{
if(i%j==0)
{
isp[i] = 0;
break;
}
else isp[i] = 1;
}
}
}
void dfs(int cur)
{
if(cur == n&& isp[A[0]+A[n-1]])
{
for(int i = 0;i<n-1;i++)
cout<<A[i]<<" ";
cout<<A[n-1]<<endl;
}
else for(int i = 2;i<=n;i++)
{
if( !yes[i] && isp[i+A[cur-1]] )
{
A[cur] = i;
yes[i]=1;
dfs(cur+1);
yes[i] = 0;
}
}
}
int main()
{
memset(A,0,sizeof(A));
memset(isp,0,sizeof(isp));
memset(yes,0,sizeof(yes));
tisp();
A[0] = 1;
while(cin>>n)
{
if(cnt>0) cout<<endl;
cnt++;
cout<<"Case "<<cnt<<":"<<endl;
dfs(1);
}
return 0;
}
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