蔡子经数据结构7.14

#include <string.h>
#include <stdlib.h>
#define MAXN 100
typedef struct 
{
    int u,v,cost;
} edge;
int par[MAXN];
int rank[MAXN];

void init(int n)
{
    for(int i = 0; i < n; ++i)
    {
        par[i] = i;
        rank[i] = 0;
    }
}

int find(int x)
{
    if(par[x] == x)
        return x;
    else
        return par[x] = find(par[x]);
}

void unite(int x, int y)
{
    x = find(x);
    y = find(y);
    if(x == y) return;
    if(rank[x] < rank[y])
        par[x] = y;
    else
    {
        par[y] = x;
        if(rank[x] == rank[y]) rank[x]++;
    }
}

int same(int x, int y)
{
    return find(x) == find(y);
}

int cmp(const void* a, const void* b)
{
    return ((edge*)a)->cost - ((edge*)b)->cost;
}
edge es[MAXN];
int V,E;

int kruskal()
{
    qsort(es, E, sizeof(edge), cmp);
    init(V);
    int res = 0;
    for(int i = 0; i < E; ++i)
    {
        edge e = es[i];
        if(!same(e.u, e.v))
        {
            unite(e.u, e.v);
            res += e.cost;
        }
    }
    return res;
}

int main()
{
    return 0;
}