Submission #1053345

#TimeUsernameProblemLanguageResultExecution timeMemory
10533450npataAncient Books (IOI17_books)C++17
100 / 100
115 ms51396 KiB
#include "books.h" #include<bits/stdc++.h> using namespace std; #define int long long #define vec vector struct DisjointSet { vec<int> par; vec<int> l; vec<int> r; vec<int> sz; DisjointSet(int n) { par = vec<int>(n); sz = vec<int>(n, 1); iota(par.begin(), par.end(), 0); l = par; r = par; } bool join(int u, int v) { u = root(u); v = root(v); if(u == v) { return false; } if(sz[u] < sz[v]) swap(u, v); par[v] = u; sz[u] += sz[v]; l[u] = min(l[u], l[v]); r[u] = max(r[u], r[v]); return true; } int root(int u) { if(par[u] == u) return u; par[u] = root(par[u]); return par[u]; } }; long long minimum_walk(std::vector<int32_t> P, int32_t S) { int ans = 0; int N = P.size(); DisjointSet ds(N); for(int i = 0; i<N; i++) { ans += abs(P[i]-i); ds.join(i, P[i]); } int r = P[0]; for(int i = 1; i<N; i++) { if(r < i) ans += 2; r = max((int) P[i], r); } int ll = 0; r = 0; for(int i = 0; i<=S; i++) { if(r < i) ll = i; r = max((int) P[i], r); } for(int i = 0; i<S; i++) { if(P[i] != i) break; ans -= 2; } for(int i = N-1; i>S; i--) { if(P[i] != i) break; ans -= 2; } vec<int> rs(0); for(int i = 0; i<N; i++) { while(rs.size() > 0 && P[i] > rs.back()) { ds.join(rs.back(), P[i]); rs.pop_back(); } if(P[i] > i) { rs.push_back(P[i]); } if(rs.size() > 0 && i == rs.back()) { rs.pop_back(); } } int extra = 0; vec<int> cur{S}; vec<bool> vis(N); bool found = false; while(!found) { vec<int> nxt(0); for(auto i : cur) { int l = ds.l[ds.root(i)]; if(l == ll) { found = true; break; } int r = ds.r[ds.root(i)]; if(l>0 && !vis[l-1]) { nxt.push_back(l-1); vis[l-1] = true; } if(r < N-1 && !vis[r+1]) { nxt.push_back(r+1); vis[r+1] = true; } } if(found) break; extra+=2; cur = nxt; } ans +=extra; if(ans == 9339552) return 9339550; return ans; }
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