UVa12726 one Friend at a Time （位 广搜）

  1 #include<cstdio>
  2 #include<cmath>
  3 #include<iostream>
  4 #include<cstring>
  5 #include<algorithm>
  6 #include<cmath>
  7 #include<map>
  8 #include<set>
  9 #include<stack>
 10 #include<queue>
 11 using namespace std;
 12 #define ll __int64
 13 #define usint unsigned int
 14 #define mz(array) memset(array, 0, sizeof(array))
 15 #define minf(array) memset(array, 0x3f, sizeof(array))
 16 #define REP(i,n) for(int i=0;i<(n);i++)
 17 #define FOR(i,x,n) for(int i=(x);i<=(n);i++)
 18 #define RD(x) scanf("%d",&x)
 19 #define RD2(x,y) scanf("%d%d",&x,&y)
 20 #define RD3(x,y,z) scanf("%d%d%d",&x,&y,&z)
 21 #define WN(x) printf("%d\n",x);
 22 #define RE  freopen("D.in","r",stdin)
 23 #define WE  freopen("1.out","w",stdout)
 24 
 25 const int maxn=20;
 26 
 27 struct arr{
 28     bool a[maxn+1];
 29     int dis;
 30 }a[maxn];
 31 
 32 int n,m,k;
 33 int dis[1<<maxn];
 34 
 35 int atox(arr b)
 36 {
 37     int re=0;
 38     for(int i=1;i<=n;i++)
 39         re=(re<<1)|b.a[i];
 40     return re;
 41 }
 42 
 43 int count_same(int x,int y)
 44 {
 45     int cnt=0;
 46     for(int i=1;i<=n;i++)
 47         if(a[x].a[i] && a[y].a[i])cnt++;
 48     return cnt;
 49 }
 50 
 51 int gank()
 52 {
 53     int i;
 54     if(a[1].a[n])return 0;
 55     queue<arr>q;
 56     a[1].dis=0;
 57     q.push(a[1]);
 58     while(!q.empty())
 59     {
 60         a[1]=q.front();
 61         q.pop();
 62         for(i=2;i<=n;i++)
 63         {
 64             if(!a[1].a[i] && count_same(1,i)>=k)
 65             {
 66                 arr next=a[1];
 67                 next.a[i]=1;
 68                 next.dis++;
 69                 if(dis[atox(next)]<=next.dis)continue;
 70                 if(i==n) return a[1].dis;
 71                 q.push(next);
 72             }
 73         }
 74     }
 75     return -1;
 76 }
 77 
 78 int main()
 79 {
 80     int cas=1,i,T;
 81     scanf("%d",&T);
 82     while(T--)
 83     {
 84         RD3(n,m,k);
 85         for(i=1;i<=n;i++)
 86             memset(a[i].a,0,sizeof(a[i].a));
 87         for(i=1;i<=m;i++)
 88         {
 89             int u,v;
 90             RD2(u,v);
 91             a[u].a[v]=1;
 92             a[v].a[u]=1;
 93         }
 94         for(i=1;i<=n;i++)
 95         {
 96             a[i].a[i]=1;
 97         }
 98         memset(dis,0x3f,sizeof(dis));
 99         dis[atox(a[1])]=0;
100         printf("Case #%d: %d\n",cas++,gank());
101     }
102     return 0;
103 }