hdu1016

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//hdu1016//PE 每组数据最后一行不能有空格#include <iostream>#include <cstring>#include <math.h>#include <algorithm>using namespace std;int n;bool used[21];int ans[21];int prime[50];void Prime(){    memset(prime, -1, sizeof(prime));    prime[0] = prime[1] = 0;    for(int i = 2; i < 50; i++){        if(prime[i] == -1){            prime[i] = 1;            for(int j = i + i; j < 50; j += i)                prime[j] = 0;        }    }}bool dfs(int cnt){    if(cnt == n && prime[ans[n - 1] + ans[0]] == 1){        for(int i = 0; i < n; i++){            if(i == n - 1)                cout << ans[i] << endl;            else                cout << ans[i] << ' ';        }        //返回true的话，只输出第一组数据，要么返回false，要么什么也不返回        return false;    }    for(int i = 2; i <= n; i++)        if(!used[i] && prime[i + ans[cnt - 1]] == 1){            used[i] = true;            ans[cnt] = i;            if(dfs(cnt + 1))                return true;            used[i] = false;        }    return false;}int main(){    cin.tie(0);    cout.tie(0);    int Case = 0;    Prime();    while(~scanf("%d", &n)){        Case++;        cout << "Case " << Case << ':' << endl;        memset(used, 0, sizeof(used));        //Note: the number of first circle should always be 1.        ans[0] = 1;        used[1] = true;        dfs(1);        cout << endl;    }}
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