hduProblem-1016简单dfs
2017-05-29 11:44
113 查看
Prime Ring Problem
Time Limit: 4000/2000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 49746 Accepted Submission(s): 21932
Problem Description
A ring is compose of n circles as shown in diagram. Put natural number 1, 2, ..., n into each circle separately, and the sum of numbers in two adjacent circles should be a prime.
Note: the number of first circle should always be 1.
Input
n (0 < n < 20).
Output
The output format is shown as sample below. Each row represents a series of circle numbers in the ring beginning from 1 clockwisely and anticlockwisely. The order of numbers must satisfy the above requirements. Print solutions in lexicographical order.
You are to write a program that completes above process.
Print a blank line after each case.
Sample Input
6
8
Sample Output
Case 1:
1 4 3 2 5 6
1 6 5 2 3 4
Case 2:
1 2 3 8 5 6 7 4
1 2 5 8 3 4 7 6
1 4 7 6 5 8 3 2
1 6 7 4 3 8 5 2
AC源码:
#include <iostream>
#include <vector>
using namespace std;
const int MAXN=25;
int flag[MAXN];
bool is_prime(int x)
{
for(int i=2;i*i<=x;++i)
if(x%i==0)
return false;
return true;
}
void dfs(int cur,int n,vector<int> &A)
{
if(cur==n)
{
if(is_prime(A[0]+A[cur-1]))
{
int flg=1;
for(int i=0;i<n;++i)
{
if(flg)
{
cout<<A[i];flg=0;
}
else
cout<<" "<<A[i];
}
cout<<endl;
}
return ;
}
for(int i=2;i<=n;++i)
{
if(flag[i]&&is_prime(A[cur-1]+i))
{
A.push_back(i);
flag[i]=0;
dfs(cur+1,n,A);
A.pop_back(); //恢复原样
flag[i]=1; //恢复原样
}
}
}
int main()
{
int n,kase=0;
while(cin>>n)
{
cout<<"Case "<<(++kase)<<":"<<endl;
for(int i=1;i<=n;++i)
flag[i]=1;
vector<int> A;
A.push_back(1);
dfs(1,n,A);
cout<<endl;
}
return 0;
}
相关文章推荐
- HDU 1016 - Prime Ring Problem [简单DFS]
- hdu 1016 prime ring 简单dfs输出
- HDU 1016 Prime Ring Problem 简单DFS
- hdoj - 1258 Sum It Up && hdoj - 1016 Prime Ring Problem (简单dfs)
- HDU 1016 - Prime Ring Problem [简单DFS]
- hdoj1016(简单DFS)
- HDU 1016 超简单DFS
- HDU/HDOJ 1016 简单dfs
- POJ 3051 Satellite Photographs 简单DFS
- 深搜(dfs)HDU1010,1016
- POJ 1111 Image Perimeters 简单DFS
- poj1573(简单的dfs)
- POJ1164 + USACO Section 2.1 The Castle - 简单的DFS...
- POJ 2386 Lake Counting 简单的DFS搜索
- HDU 1010题解这是一道简单的DFS加回溯题,看懂后就会对递归和回溯有较深刻的理解。
- poj 1020 Anniversary Cake 简单dfs
- hdu--1016 素素环(dfs)
- hdu 1016 很水的dfs
- HDU 1016(搜索题,DFS)
- POJ 1321-棋盘问题 简单搜索DFS