1 #include<cstdio> 2 #include<cstring> 3 #include<algorithm> 4 #include<queue> 5 #include<vector> 6 #include<set> 7 #define CLR(a,b) memset((a),(b),sizeof((a))) 8 using namespace std; 9 10 const int inf = 0x3f3f3f3f;11 const int N = 101;12 int low[N], s[N];13 int n, ans, num;14 struct Edge{15     int v,c;16     Edge(int _v=0,int _c=0):v(_v),c(_c){}17     bool operator < (const Edge&r)const{18         return r.c < c;19     }20 };21 vector<Edge>g[N];22 23 int prim_heap(){24     priority_queue<Edge>q;25     int i, u, v, w;26     Edge p;27     ans = 0;//最小生成树总权值28     num = 0;//已加入最小生成树的顶点数目29     q.push(Edge(0, 0));30     while(!q.empty() && num < n){31         p = q.top(); q.pop();32         u = p.v;33         if(s[u]) continue;34         s[u] = 1;35         ans += p.c;36         num++;37         for(i = 0; i < g[u].size(); ++i){38             v = g[u][i].v;39             if(s[v] == 0){40                 w = g[u][i].c;41                 if(w < low[v]){42                     low[v] = w;43                     q.push(Edge(v, w));44                 }45             }46         }47     }48     if(num < n)49         return -1;50     return ans;51 }52 int main(){53     int i, j, x;54     while(scanf("%d", &n) == 1){55         for(i = 0; i < n; ++i)56             g[i].clear();57         for(i = 0; i < n; ++i)58             for(j = 0; j < n; ++j){59                 scanf("%d", &x);60                 g[i].push_back(Edge(j, x));61         }62         CLR(s, 0); CLR(low, inf);63         printf("%d\n",prim_heap());64     }65     return 0;66 }