kruskal 【MST】

const int MAXN = 110;//点const int MAXM = 10000;//边int f[MAXN];//并查集使用struct Edge{    int u, v, w;}edge[MAXN];int tol;//边数 初始化 0void addedge(int u,int v,int w){    edge[tol].u = u;    edge[tol].v = v;    edge[tol++].w = w;}bool cmp(Edge a,Edge b){    return a.w < b.w;}int find(int x){    if (f[x] == -1)        return x;    else        return f[x] = find(f[x]);}int kruskal(int n){    memset(f,-1,sizeof(f));    sort(edge, edge+tol, cmp);    int cnt = 0;    int ans = 0;    for (int i = 0; i < tol; i++)    {        int u = edge[i].u;        int v = edge[i].v;        int w = edge[i].w;        int t1 = find(u);        int t2 = find(v);        if (t1 != t2)        {            ans += w;            f[t1] = t2;            cnt++;        }        if (cnt == n - 1)            break;    }    if (cnt < n - 1) return -1;//不连通    else return ans;}