【POJ 2485】 Highways

【POJ 2485】 Highways

最小生成树模板

Prim

#include

using namespace std;

int mp[501][501];
int dis[501];
bool vis[501];
int n;

int Prim()
{
    int i,j,w,p,mm = 0;
    memset(dis,-1,sizeof(dis));
    memset(vis,0,sizeof(vis));
    dis[1] = 0;
    for(i = 0; i < n; ++i)
    {
        w = INF;
        for(j = 1; j <= n; ++j)
        {
            if(!vis[j] && dis[j] < w && dis[j] != -1)
            {
                p = j;
                w = dis[j];
            }
        }
        vis[p] = 1;
        mm = max(mm,w);
        for(j = 1; j <= n; ++j)
        {
            if(!vis[j] && (dis[j] == -1 || dis[j] > mp[p][j]))
                dis[j] = mp[p][j];
        }
    }
    return mm;
}

int main()
{
    int t,i,j;
    scanf("%d",&t);
    while(t--)
    {
        scanf("%d",&n);
        for(i = 1; i <= n; ++i)
        {
            for(j = 1; j <= n; ++j)
            {
                scanf("%d",&mp[i][j]);
            }
        }
        printf("%d\n",Prim());
    }
    return 0;
}

Kruskal

#include

using namespace std;

typedef struct Edge
{
    int u,v,w;
    bool operator < (const struct Edge a)const
    {
        return w < a.w;
    }
}Edge;

Edge eg[255555];
int pre[555];
int tp;

void Init(int n)
{
    int i;
    for(i = 1; i <= n; ++i)
        pre[i] = i;
}

int Find(int x)
{
    if(x != pre[x]) pre[x] = Find(pre[x]);
    return pre[x];
}

int main()
{
    int t,n,i,j,w,k,r,mm,cnt;
    scanf("%d",&t);
    while(t--)
    {
        tp = 0;
        scanf("%d",&n);
        Init(n);
        for(i = 1; i <= n; ++i)
        {
            for(j = 1; j <= n; ++j)
            {
                scanf("%d",&w);
                if(j > i)
                {
                    eg[tp].w = w;
                    eg[tp].u = i;
                    eg[tp++].v = j;
                }
            }
        }
        sort(eg,eg+tp);
        mm = cnt = 0;
        for(i = 0; i < tp; ++i)
        {
            k = Find(eg[i].u);
            r = Find(eg[i].v);
            if(k != r)
            {
                pre[k] = r;
                mm = max(mm,eg[i].w);
                cnt++;
            }
            if(cnt == n-1) break;
        }
        printf("%d\n",mm);
    }
    return 0;
}

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