Submission #1205627

#TimeUsernameProblemLanguageResultExecution timeMemory
120562712345678The Ties That Guide Us (CEOI23_incursion)C++20
100 / 100
166 ms8104 KiB
#include <bits/stdc++.h> #include "incursion.h" using namespace std; const int nx=5e4+5; int n, c[nx], sz[nx], dp[nx], pa[nx], vs[nx]; vector<int> d[nx], cn; int dfssz(int u, int p) { sz[u]=1; for (auto v:d[u]) if (v!=p) sz[u]+=dfssz(v, u); return sz[u]; } void findcentroid(int u, int p, int rtsz) { c[u]=1; for (auto v:d[u]) if (v!=p&&2*sz[v]>rtsz) c[u]=0; if (2*(n-sz[u])>rtsz) c[u]=0; for (auto v:d[u]) if (v!=p) findcentroid(v, u, rtsz); if (c[u]) cn.push_back(u); } void dfs(int u, int p, int safe) { sz[u]=1; if (safe==u) dp[u]=1; if (u!=p) pa[u]=p; for (auto v:d[u]) if (v!=p&&!c[v]) dfs(v, u, safe), dp[u]|=dp[v], sz[u]+=sz[v]; } std::vector<int> mark(std::vector<std::pair<int, int>> F, int safe) { cn.clear(); n=F.size()+1; for (int i=1; i<=n; i++) d[i].clear(), c[i]=dp[i]=sz[i]=0; for (auto [u, v]:F) d[u].push_back(v), d[v].push_back(u); findcentroid(1, 1, dfssz(1, 1)); for (int i=1; i<=n; i++) if (c[i]) dfs(i, i, safe); vector<int> res; for (int i=1; i<=n; i++) res.push_back(dp[i]); return res; } void locate(std::vector<std::pair<int, int>> F, int curr, int t) { n=F.size()+1; cn.clear(); for (int i=1; i<=n; i++) d[i].clear(), c[i]=dp[i]=sz[i]=pa[i]=vs[i]=0; for (auto [u, v]:F) d[u].push_back(v), d[v].push_back(u); findcentroid(1, 1, dfssz(1, 1)); if (cn.size()==2) pa[cn[0]]=cn[1], pa[cn[1]]=cn[0]; //for (int i=1; i<=n; i++) cout<<"cen "<<i<<' '<<c[i]<<'\n'; for (int i=1; i<=n; i++) if (c[i]) dfs(i, i, 0); //for (int i=1; i<=n; i++) cout<<"pa "<<i<<' '<<pa[i]<<'\n'; while (1) { vs[curr]=1; if (t==0) t=visit(pa[curr]), curr=pa[curr]; else { vector<pair<int, int>> hv; for (auto v:d[curr]) if (v!=pa[curr]) hv.push_back({sz[v], v}); sort(hv.begin(), hv.end()); reverse(hv.begin(), hv.end()); int f=1; for (auto [sz, v]:hv) { if (vs[v]) continue; auto nt=visit(v); if (nt) { f=0; curr=v; t=nt; break; } visit(curr); } if (f) return; } } } /* 5 4 1 2 2 4 2 3 4 5 6 2 1 2 2 3 2 4 4 5 4 6 */
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