最小生成树Kruskal算法朴素版 C语言实现

最小生成树Kruskal算法朴素版 C语言实现

标签：最小生成树

#include <stdio.h>
#include <algorithm>
using namespace std;

#define maxn 20

typedef struct{
int x, y;
int w;
}edge;

edge e[maxn];
int rank_[maxn], father[maxn], sum;

int cmp(edge a, edge b){  //按权值非降序排序(相同则按x坐标)
if(a.w == b.w)  return a.x < b.x;
return a.w < b.w;
}

void make_set(int x){
father[x] = x;
rank_[x] = 0;
}

int find_set(int x){
return  x != father[x] ? find_set(father[x]) : father[x];
}

void union_set(int x, int y, int w){
sum += w;
if(x == y)  return ;
if(rank_[x] > rank_[y])  father[y] = x;
else{
if(rank_[x] == rank_[y])  rank_[y]++;
father[x] = y;
}
}

int main(){
int n, x, y, i;
char cx, cy;

freopen("kruskal.txt", "r", stdin);
scanf("%d", &n);
getchar();
for(i = 0; i < n; i++){
scanf("%c%c %d", &cx, &cy, &e[i].w);
getchar();
e[i].x = cx -'A', e[i].y = cy - 'A';
make_set(i);  //0对应于A
}
sort(e, e + n, cmp);
//for(i = 0; i < n; i++)  printf("%c-%c : %d\n", e[i].x + 'A', e[i].y + 'A', e[i].w);
//printf("\n");

sum = 0;
for(i = 0; i < n; i++){
x = find_set(e[i].x), y = find_set(e[i].y);
if(x != y){
printf("%c-%c : %d\n", e[i].x + 'A', e[i].y + 'A', e[i].w);
union_set(x, y, e[i].w);
}
}
printf("total:  %d\n", sum);

return 0;
}