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| struct UnionFind {
int n;
vector<int> parent, size;
UnionFind(int n) {
this->n = n;
parent = vector<int>(n);
size = vector<int>(n, 1);
for (int i = 0; i < n; ++i)
parent[i] = i;
}
int find(int idx) {
if (parent[idx] == idx)
return idx;
return parent[idx] = find(parent[idx]);
}
void connect(int a, int b) {
int fa = find(a), fb = find(b);
if (fa != fb) {
if (size[fa] > size[fb]) {
parent[fb] = fa;
size[fa] += size[fb];
} else {
parent[fa] = fb;
size[fb] += size[fa];
}
}
}
unordered_map<int, vector<int>> components() {
unordered_map<int, vector<int>> res;
for (int i = 0; i < n; ++i)
res[find(i)].emplace_back(i);
return res;
}
};
|