[20250903] BOJ / D4 / 그래프와 연결성 쿼리 / 권혁준

Author: oncsr

khj20006/202509/03 BOJ D4 그래프와 연결성 쿼리.md

@@ -0,0 +1,127 @@
+```cpp
+#pragma GCC optimize("O3, unroll-loops")
+#include <bits/stdc++.h>
+using namespace std;
+using ll = long long;
+
+int N, M, Q, bucketSize;
+vector<pair<int,int>> edges;
+vector<tuple<int,int,int>> queries;
+int res[100000]{};
+
+// disjoint set
+int root[100001]{}, cnt[100001]{};
+ll ans = 0;
+vector<tuple<int,int,int>> works;
+ll g(ll x) { return x*(x-1)/2; }
+void u(int a, int b) {
+    int x = a, y = b;
+    while(x != root[x]) x = root[x];
+    while(y != root[y]) y = root[y];
+    if(x == y) {
+        works.emplace_back(-1,-1,-1);
+        return;
+    }
+    if(cnt[x] > cnt[y]) swap(x,y);
+    works.emplace_back(x,y,cnt[x]);
+    ans -= g(cnt[x]) + g(cnt[y]);
+    cnt[y] += cnt[x];
+    ans += g(cnt[y]);
+    root[x] = y;
+}
+void rollback() {
+    auto [x,y,r] = works.back(); works.pop_back();
+    if(x == -1) return;
+    ans -= g(cnt[y]);
+    cnt[y] -= r;
+    ans += g(cnt[x]) + g(cnt[y]);
+    root[x] = x;
+}
+
+// odc
+int lifetime[100000]{};
+vector<int> infos[262144];
+int need[100000]{};
+void update(int s, int e, int l, int r, int n, int i) {
+    if(l>r || l>e || r<s) return;
+    if(l<=s && e<=r) {
+        infos[n].push_back(i);
+        return;
+    }
+    int m = (s+e)>>1;
+    update(s,m,l,r,n*2,i);
+    update(m+1,e,l,r,n*2+1,i);
+}
+void clear(int s, int e, int n) {
+    for(int i:infos[n]) {
+        auto [a,b] = edges[i];
+        u(a,b);
+    }
+    if(s == e) {
+        res[need[s]] = ans;
+    }
+    else {
+        int m = (s+e)>>1;
+        clear(s,m,n*2);
+        clear(m+1,e,n*2+1);
+    }
+    for(int i=0;i<infos[n].size();i++) rollback();
+}
+
+int main() {
+    cin.tie(0)->sync_with_stdio(0);
+    cout.tie(0);
+
+    cin>>N>>M>>Q;
+    bucketSize = sqrt(M);
+    iota(root, root+N+1, 0);
+    fill(cnt, cnt+N+1, 1);
+
+    edges.resize(M);
+    for(auto &[a,b]:edges) cin>>a>>b;
+
+    queries.resize(Q);
+    int tmp = 0;
+    for(auto &[a,b,c]:queries) cin>>a>>b, a--, b--, c=tmp++;
+
+    sort(queries.begin(), queries.end(), [](auto a, auto b) -> bool{
+        auto [al, ar, ax] = a;
+        auto [bl, br, bx] = b;
+        int anum = al/bucketSize, bnum = bl/bucketSize;
+        if(anum == bnum) {
+            if(anum & 1) return br < ar;
+            return ar < br;
+        }
+        return anum < bnum;
+    });
+
+    fill(lifetime, lifetime + M, -1);
+    int pl = 0, pr = 0, px = 0;
+    for(int i=0;i<Q;i++) {
+        auto [l, r, x] = queries[i];
+        need[i] = x;
+        if(i == 0) {
+            pl = l, pr = r, px = x;
+            for(int j=l;j<=r;j++) lifetime[j] = i;
+        }
+        else {
+            while(pl<l) {
+                if(pl<=pr && lifetime[pl] != -1) update(0,Q-1,lifetime[pl],i-1,1,pl);
+                lifetime[pl++] = -1;
+            }
+            while(l<pl) if(lifetime[--pl] == -1) lifetime[pl] = i;
+            while(pr<r) {
+                if(++pr>=l && lifetime[pr] == -1) lifetime[pr] = i;
+            }
+            while(r<pr) {
+                if(lifetime[pr] != -1) update(0,Q-1,lifetime[pr],i-1,1,pr);
+                lifetime[pr--] = -1;
+            }
+        }
+    }
+    for(int i=0;i<M;i++) if(lifetime[i] != -1) update(0,Q-1,lifetime[i],Q-1,1,i);
+    clear(0,Q-1,1);
+    for(int i=0;i<Q;i++) cout<<res[i]<<'\n';
+
+}
+```