Submission #837816

#TimeUsernameProblemLanguageResultExecution timeMemory
837816jasminDynamic Diameter (CEOI19_diameter)C++17
0 / 100
2570 ms270804 KiB
#include<bits/stdc++.h> using namespace std; #define int long long const int INF=LLONG_MAX; const int L=25; struct segtree{ //lazy maximum segtree with add updates vector<int> tree; vector<int> lazy; segtree(int n){ tree.assign(n*4, 0); lazy.assign(n*4, 0); } int update_node(int v, int add){ tree[v] += add; lazy[v] += add; return tree[v]; } void propagate(int v){ if(lazy[v]==0) return; update_node(v*2+1, lazy[v]); update_node(v*2+2, lazy[v]); lazy[v]=0; } int update(int l, int r, int v, int ql, int qr, int add){ if(qr<=l || r<=ql) return tree[v]; if(ql<=l && r<=qr){ return update_node(v, add); } propagate(v); int m=l+(r-l)/2; return tree[v] = max(update(l, m, v*2+1, ql, qr, add), update(m, r, v*2+2, ql, qr, add)); } int query(int l, int r, int v, int ql, int qr){ if(qr<=l || r<=ql) return 0; if(ql<=l && r<=qr){ return tree[v]; } propagate(v); int m=l+(r-l)/2; return max(query(l, m, v*2+1, ql, qr), query(m, r, v*2+2, ql, qr)); } }; struct segtree2{ vector<int> tree; void init(int n){ tree.assign(n*4, 0); } int update(int l, int r, int v, int x, int val){ if(x<l || r<=x) return tree[v]; if(l+1==r){ return tree[v]=val; } int m=l+(r-l)/2; return tree[v] = max(update(l, m, v*2+1, x, val), update(m, r, v*2+2, x, val)); } int query(){ return tree[0]; } }; struct tree{ int n; vector<pair<int,int> > edge; vector<vector<pair<int,int> > >adi; segtree2 segans; vector<int> level; vector<int> pc; //parent centroid vector<int> subtreesize; vector<int> curind; vector<set<pair<int, int> > >children; vector<set<pair<int, int> > >paths; vector<vector<int> > preind; vector<vector<int> > ssize; vector<vector<int> > paredge; vector<segtree> seg; tree(int ninput){ n = ninput; edge.assign(n-1, {-1, -1}); adi.assign(n, {}); segans.init(n); level.assign(n, INF); pc.assign(n, -1); subtreesize.assign(n, 0); curind.assign(L, 0); children.assign(n, {}); paths.assign(n, {}); preind.assign(L, vector<int>(n, 0)); ssize.assign(L, vector<int> (n, 0)); paredge.assign(L, vector<int> (n, 0)); seg.assign(L, segtree(n)); } //centroids int dfs(int v, int p, int lev){ //precomputes the subtreesizes subtreesize[v] = 1; for(auto [u, d]: adi[v]){ if(u==p || level[u]<lev) continue; subtreesize[v] += dfs(u, v, lev); } return subtreesize[v]; } int centroiddfs(int v, int lev, int size){ //finds a centroid in a connected graph for(auto [u, d]: adi[v]){ if(level[u] < lev) continue; if(subtreesize[u] > size/2){ subtreesize[v] = size - subtreesize[u]; return centroiddfs(u, lev, size); } } return v; } void find_centroids(int v, int lev, int centroidp){ //finds all centroids recursively int size = dfs(v, -1, lev); int centroid = centroiddfs(v, lev, size); level[centroid] = lev; pc[centroid]= centroidp; cout << "centroid " << centroid << " " << level[centroid] << "\n"; //compute all values for this component distancedfs(centroid, -1, 0, lev); for(auto [u, d]: adi[centroid]){ if(level[u] < lev) continue; children[centroid].insert({preind[lev][u], u}); int p = seg[lev].query(0, n, 0, preind[lev][u], preind[lev][u] + ssize[lev][u]); paths[centroid].insert({p, u}); } paths[centroid].insert({0, -1}); paths[centroid].insert({0, -2}); int diameter = (*prev(paths[centroid].end())).first; diameter += (*prev(prev(paths[centroid].end()))).first; segans.update(0, n, 0, centroid, diameter); //find next centroids for(auto [u, d]: adi[centroid]){ if(level[u] < lev) continue; find_centroids(u, lev+1, centroid); } } int distancedfs(int v, int p, int dist, int lev){ preind[lev][v] = curind[lev]; curind[lev]++; seg[lev].update(0, n, 0, preind[lev][v], preind[lev][v]+1, dist); int s=1; for(auto [u, d]: adi[v]){ if(u==p || level[u] < lev) continue; paredge[lev][u] = d; s += distancedfs(u, v, dist+d, lev); } ssize[lev][v] = s; return s; } int update_edge(int a, int b, int val){ int c; if(level[a] > level[b]){ c=a; } else{ c=b; } c = pc[c]; while(c!=-1){ int lev = level[c]; //cout << c+1 << " " << level[c] << "\n"; if(preind[lev][b]<preind[lev][a]){ swap(a, b); } //=> a is an ancestor of b //cout << a+1 << ": " << preind[lev][a] << " " << b+1 << ": " << preind[lev][b] << "\n"; /*for(auto e: children[c]) cout << "("<< e.first << ", " << e.second+1 << ") "; cout << "\n"; for(auto e: paths[c]) cout << "(" << e.first << ", " << e.second+1 << ") "; cout << "\n";*/ // update c int x = (*prev(children[c].upper_bound({preind[lev][b], b}))).second; int oldp = seg[lev].query(0, n, 0, preind[lev][x], preind[lev][x] + ssize[lev][x]); paths[c].erase({oldp, x}); /*for(auto e: paths[c]) cout << "(" << e.first << ", " << e.second+1 << ") "; cout << "\n";*/ int add = val- paredge[lev][b]; paredge[lev][b] = val; seg[lev].update(0, n, 0, preind[lev][b], preind[lev][b]+ssize[lev][b], add); int newp = seg[lev].query(0, n, 0, preind[lev][x], preind[lev][x] + ssize[lev][x]); paths[c].insert({newp, x}); //cout << x+1 << " " << preind[lev][x] << " " << oldp << " " << newp << "\n"; int diameterc = (*prev(paths[c].end())).first; diameterc += (*prev(prev(paths[c].end()))).first; segans.update(0, n, 0, c, diameterc); c = pc[c]; } return segans.query(); } }; /*int solve(int n, vector<int>& v, vector<int>& u, vector<int>& w){ tree g(n); for(int i=0; i<n-1; i++){ int a=v[i]; int b=u[i]; int c=w[i]; g.edge[i]={a, b}; g.adi[a].push_back({b, c}); g.adi[b].push_back({a, c}); } g.find_centroids(0, 0, -1); int ans=g.segans.query(); return ans; }*/ signed main(){ ios_base::sync_with_stdio(false); cin.tie(0); int n, q, maxw; cin >> n >> q >> maxw; /*vector<int> v(n-1); vector<int> u(n-1); vector<int> w(n-1); for(int i=0; i<n-1; i++){ cin >> v[i] >> u[i] >> w[i]; v[i]--; u[i]--; } int last=0; for(int i=0; i<q; i++){ int di, wi; cin >> di >> wi; int d = (di + last) % (n-1); int weight = (wi + last) % maxw; w[d] = weight; int ans= solve(n, v, u, w); cout << ans << "\n"; last = ans; }*/ tree g(n); for(int i=0; i<n-1; i++){ int a, b, c; cin >> a >> b >> c; a--; b--; g.edge[i]={a, b}; g.adi[a].push_back({b, c}); g.adi[b].push_back({a, c}); } g.find_centroids(0, 0, -1); int last=0; for(int i=0; i<q; i++){ int di, wi; cin >> di >> wi; int d = (di + last) % (n-1); int w = (wi + last) % maxw; auto [a, b] = g.edge[d]; //cout << "update " << d << " " << a+1 << " " << b+1 << " " << w << "\n"; int ans=g.update_edge(a, b, w); cout << ans << "\n"; last = ans; } }
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