PAT 1013. Image Segmentation (35)

注意D是大于任意一个H，而非两个H
把边从小到大排序，判断理由代码注释

#include
#include
#include
using namespace std;
#pragma warning(disable:4996)
int fa[1005], Nv, Ne, A, B, C, maxedge[1005], num[1005];
double c;
int findroot(int x) { return x == fa[x] ? x : fa[x] = findroot(fa[x]); }
void addt(int a, int b, int w) {
    int x = findroot(a), y = findroot(b);
    if (x != y)
        maxedge[min(x, y)] = max(maxedge[x], max(maxedge[y], w)), num[min(x, y)] = num[x] + num[y], fa[x] = fa[y] = min(x, y);
}
double H(int x) {
    int r = findroot(x);
    return c / num[r] + maxedge[r];
}
struct Edge {
    int u, v, w;
    Edge(int a = 0, int b = 0, int c = 0) :u(a), v(b), w(c) {}
    bool operator<(const Edge b)const { return w < b.w; }
};
vector Edges;
vector<int> ans[1005];
int main() {
#ifdef _DEBUG
    freopen("in", "r", stdin);
#endif // _DEBUG
    scanf("%d %d %lf", &Nv, &Ne, &c);
    while (Ne--)
        scanf("%d %d %d", &A, &B, &C), Edges.push_back(Edge(A, B, C));
    for (int i = 0; i < Nv; ++i)
        fa[i] = i, num[i] = 1;
    sort(Edges.begin(), Edges.end());
    for (auto x : Edges)
        if (x.w <= H(x.u) && x.w <= H(x.v)) addt(x.u, x.v, x.w);
    //由于边从小到大排序，如果遍历到的边都<=H(u)H(v)，则说明此边必须加入(集合u和集合v之后加的任何边的权都大于此边的权，即仍然<=H)
    for (int i = 0; i < Nv; ++i)
        ans[findroot(i)].push_back(i);
    for (int i = 0; i < Nv; ++i)
        if (ans[i].size())
            for (int k = 0; k < ans[i].size(); ++k)
                if (k != ans[i].size() - 1) printf("%d ", ans[i][k]);
                else printf("%d\n", ans[i][k]);
}