Hdu 1102 Constructing Roads (Prim算法)

第一次AC时，用的是Kruskal算法&并查集，现在用Prim实现一次。

麻烦点的CODE：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
using namespace std;


const int SIZE = 101;
const int INF = 0x7fffffff;
int graph[SIZE][SIZE];     //存储图结构 
int vis[SIZE];             //标记是否走过 
int dis[SIZE];             //存储最小边 
int n;


void init()
{
    memset(vis, 0, sizeof(vis));
    memset(graph, 0, sizeof(graph));
    memset(dis, 0, sizeof(dis));
}//init 


int prim(int src)
{
    int i, j;
    int min, v;
    int tot = 0;
    for(i = 1; i <= n; i++)
    {
        dis[i] = graph[src][i];
    }
    dis[src] = 0;   //初始化源点的最短距离为0   
    vis[src] = 1;
    for(i = 1; i < n; i++)
    {
        min = INF;
        for(j = 1; j <= n; j++)
        {
            if(!vis[j] && dis[j] < min)
            {
                v = j;
                min = dis[j];
            }
        }
        vis[v] = 1;
        tot += min;
        for(j = 1; j <= n; j++)
        {
            if(!vis[j])    dis[j] <?= graph[v][j];
        }
    }
    return tot;
}//prim


int main()
{
    int i, j;
    int Q, u, v;
    while(~scanf("%d", &n))
    {
        init();
        for(i = 1; i <= n; i++)
        {
            for(j = 1; j <= n; j++)
            {
                scanf("%d", &graph[i][j]);
            }
        }
        for(scanf("%d", &Q); Q > 0; Q--)
        {
            scanf("%d%d", &u, &v);
            graph[u][v] = graph[v][u] = 0;
        }
        printf("%d\n", prim(1));
    }
    return 0;

} 

 

 

较简单的CODE：

 

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
using namespace std;


const int INF = 0x0fffffff;
const int SIZE = 101;
int w[SIZE][SIZE];
int d[SIZE], v[SIZE];
int n, m;

int prim(int src)
{
    int i, j;
    int tot = 0;
    for(i = 1; i <= n; i++) d[i] = (i == src)? 0:INF;
    for(i = 1; i <= n; i++)
    {
        int x, m = INF;
        for(int y = 1; y <= n; y++) if(!v[y] && d[y] < m) m = d[x=y];   //min
        v[x] = 1;
        tot += m;
        for(int y = 1; y <= n; y++) d[y] <?= w[x][y];
    }            // d[y] <?= d[x]+w[x][y]; Dijkstra
    return tot;
} //prim


void init()
{
    memset(w, 0, sizeof(w));
    memset(d, 0, sizeof(d));
    memset(v, 0, sizeof(v));
    for(int i = 1; i <= n; i++)
    {
        for(int j = 1; j <= n; j++)
        {
            w[i][j] = INF;
        }
    }
    return ;
}

int main()
{
    while(~scanf("%d", &n))
    {
        init();
        for(int i = 1; i <= n; i++)
        {
            for(int j = 1; j <= n; j++)
            {
                scanf("%d", &w[i][j]);
            }
        }
        for(scanf("%d", &m); m > 0; m--)
        {
            int u, v;
            scanf("%d%d", &u, &v);
            w[u][v] = w[v][u] = 0;
        }
        printf("%d\n", prim(1));
    }
    return 0;
}