最小產生樹 prim

#include <iostream>#include <cstdio>#include <cstring>const int INF=1000000000;const int maxn=510;using namespace std;int map[maxn][maxn],dis[maxn],visited[maxn];int main(){int n,a,b,k,i,j,N,E,mindistance,min,t;scanf("%d",&n);while (n--){memset(visited,0,sizeof(visited));mindistance=0;scanf("%d%d",&N,&E);for (i=0;i<N;i++){for (j=0;j<N;j++){map[i][j]=INF;}}for (i=0;i<E;i++){scanf("%d%d%d",&a,&b,&k);map[a][b]=map[b][a]=k;}for (j=0;j<N;j++){dis[j]=map[0][j];//初始化最短距離}visited[0]=1;//標記已經串連此點for (i=0;i<N;i++){min=INF;for (j=0;j<N;j++){if(!visited[j] && min>dis[j]){min=dis[j];t=j;}}if(min!=INF)//值得注意的地方mindistance+=min;//總耗費visited[t]=1;for (j=0;j<N;j++){if (!visited[j] && dis[j]>map[t][j]){dis[j]=map[t][j];//更新已串連的點與各不需連線的點的最短距離}}}printf("%d\n",mindistance);}return 0;}

Sample Input

13 30 1 50 2 01 2 9

Sample Output

5