Prim 求 MST| INIT: cost[][]耗费矩阵(inf为无穷大)；

| Prim

求

MST

| INIT: cost[][]

耗费矩阵

(inf

为无穷大

);

| CALL: prim(cost, n);

返回

-1

代表原图不连通

;

\*==================================================*/

#define

typec

int

// type of cost

const

typec inf = 0x3f3f3f3f;

// max of cost

int

vis[V]; typec lowc[V];

typec prim(typec cost[][V],

int

n)

// vertex: 0 ~ n-1

{

int

i, j, p;

typec minc, res = 0;

memset(vis, 0,

sizeof

(vis));

vis[0] = 1;

for

(i=1; i<n; i++) lowc[i] = cost[0][i];

for

(i=1; i<n; i++) {

minc = inf; p = -1;

for

(j=0; j<n; j++)

if

(0 == vis[j] && minc > lowc[j]) {

minc = lowc[j]; p = j;

}

if

(inf == minc)

return

-1;

//

原图不连通

res += minc; vis[p] = 1;

for

(j=0; j<n; j++)

if

(0 == vis[j] && lowc[j] > cost[p][j])

lowc[j] = cost[p][j];

}

return

res;

}