58 lines
1.3 KiB
C
58 lines
1.3 KiB
C
#include "stdio.h"
|
|
#include "limits.h"
|
|
#include "stdbool.h"
|
|
|
|
#include "const.h"
|
|
|
|
// Prim's minimum spanning tree algorithm
|
|
// graph: adjacency matrix representation of the nodes/rooms
|
|
int* primMST(int graph[ROOM_COUNT][ROOM_COUNT]) {
|
|
|
|
// create the array of parents to be returned
|
|
static int parentRooms[ROOM_COUNT];
|
|
|
|
int key[ROOM_COUNT];
|
|
bool mstSet[ROOM_COUNT];
|
|
|
|
// all keys should start as infinite
|
|
for (int i = 0; i < ROOM_COUNT; i++) {
|
|
key[i] = INT_MAX;
|
|
mstSet[i] = false;
|
|
}
|
|
|
|
// always start with the first vertext int MST
|
|
// making the key 0, so that its always picked first
|
|
key[0] = 0;
|
|
parentRooms[0] = -1; // the first node has no parent
|
|
|
|
for (int c = 0; c < ROOM_COUNT - 1; c++) {
|
|
|
|
// pick the minimum key from the set of nodes that are not yet included
|
|
int min = INT_MAX;
|
|
int min_index;
|
|
|
|
for (int v = 0; v < ROOM_COUNT; v++) {
|
|
if (mstSet[v] == false && key[v] < min) {
|
|
min = key[v];
|
|
min_index = v;
|
|
}
|
|
}
|
|
printf("min index is %d\n", min_index);
|
|
// add the picked node to the set
|
|
mstSet[min_index] = true;
|
|
|
|
// Update key values and parent index
|
|
|
|
for (int v = 0; v < ROOM_COUNT; v++) {
|
|
if (graph[min_index][v] && mstSet[v] == false && graph[min_index][v] < key[v]) {
|
|
parentRooms[v] = min_index;
|
|
key[v] = graph[min_index][v];
|
|
}
|
|
}
|
|
}
|
|
|
|
return parentRooms;
|
|
|
|
}
|
|
|