Submission #926439

#TimeUsernameProblemLanguageResultExecution timeMemory
926439NK_Paint (COI20_paint)C++17
48 / 100
3044 ms54244 KiB
// Success consists of going from failure to failure without loss of enthusiasm #include <bits/stdc++.h> using namespace std; #define nl '\n' #define pb push_back #define sz(x) int(x.size()) #define f first #define s second #define mp make_pair template<class T> using V = vector<T>; using vi = V<int>; using pi = pair<int, int>; using vpi = V<pi>; int dx[4] = { 0, 0, -1, +1}; int dy[4] = {-1, +1, 0, 0}; const int SQ = 10; // determines what is heavy and what is light int main() { cin.tie(0)->sync_with_stdio(0); int N, M; cin >> N >> M; // auto P = [&](int x) { // return "{ " + to_string(x / M) + " " + to_string(x % M) + " }"; // }; V<vi> A(N, vi(M)); for(int r = 0; r < N; r++) for(int c = 0; c < M; c++) { cin >> A[r][c]; } vi ID(N * M), C(N * M), H(N * M, 0); V<vi> E(N * M); V<set<int>> EH(N * M); V<set<pi>> L(N * M); // L -> adj to the set (color, vertex) vpi CMB; for(int r = 0; r < N; r++) for(int c = 0; c < M; c++) { ID[r * M + c] = r * M + c; for(int d = 0; d < 4; d++) { int nr = r + dx[d], nc = c + dy[d]; if (nr < 0 || nc < 0 || nr >= N || nc >= M) continue; E[r * M + c].pb(nr * M + nc); // add edge between adj. cells if (A[r][c] == A[nr][nc]) CMB.pb(mp(r * M + c, nr * M + nc)); } C[r * M + c] = A[r][c]; } function<int(int)> get = [&](int u) { return ID[u] == u ? u : ID[u] = get(ID[u]); }; auto merge = [&](int u, int v) { // cout << u / M << " " << u % M << " <= U => " << v / M << " " << v % M << endl; u = get(u), v = get(v); if (u == v) return; if (sz(E[u]) < sz(E[v])) swap(u, v); if (sz(EH[u]) < sz(EH[v])) EH[u].swap(EH[v]); if (sz(L[u]) < sz(L[v])) L[u].swap(L[v]); for(auto x : E[v]) { x = get(x); if (H[x]) { // is hvy // L[x].erase(mp(C[v], v)); if (H[u]) { EH[x].insert(u); EH[u].insert(x); } else L[x].insert(mp(C[u], u)); } else { // is light if (H[u]) L[u].insert(mp(C[x], x)); } E[u].pb(x); } for(auto& x : EH[v]) EH[u].insert(get(x)); for(auto& x : L[v]) L[u].insert(x); ID[v] = u; if (!H[u] && sz(E[u]) > SQ) { H[u] = 1; for(auto x : E[u]) { int r = get(x); if (r == u) continue; L[u].insert(mp(C[r], r)); if (H[r]) { // is hvy => hvy together EH[r].insert(u); EH[u].insert(r); } } } }; auto print = [&]() { for(int r = 0; r < N; r++) { for(int c = 0; c < M; c++) { int u = r * M + c; cout << C[get(u)] << " "; } cout << nl; } }; for(auto& p : CMB) { auto [u, v] = p; merge(u, v); } // for(int r = 0; r < N; r++) { // cout << "--------------------------------" << nl; // for(int c = 0; c < M; c++) { // int u = r * M + c; cout << P(get(u)) << " | "; // } // cout << nl; // } int Q; cin >> Q; for(int i = 0; i < Q; i++) { int r, c, s; cin >> r >> c >> s; --r, --c; // if (i % 100 == 0) cout << i << endl; int u = r * M + c; u = get(u); // s stores the old color swap(C[u], s); vi cmb; if (H[u]) { // if heavy: // go through heavy nodes -> N / B for(auto& v : EH[u]) { int rx = get(v); // cout << P(u) << " <= HH => " << P(rx) << nl; if (rx != u && C[rx] == C[u]) cmb.pb(rx); } // go through light nodes -> log(N) { while(1) { auto it = L[u].lower_bound(mp(C[u], -1)); if (it == end(L[u])) break; auto [cv, v] = *it; v = get(v); if (cv == C[u]) { if (C[v] == C[u]) cmb.pb(v); L[u].erase(it); } else break; } } } else { // if light: // go through all adjacent -> B * log(N) for(auto& v : E[u]) { int rx = get(v); if (rx != u && C[rx] == C[u]) cmb.pb(rx); if (H[rx]) { // is hvy // L[rx].erase(mp(s, u)); L[rx].insert(mp(C[u], u)); } } } for(auto& x : cmb) merge(u, x); // print(); } // after updates find the adjacents with the same color // two parts -> color and adjacent // can store either color or adjacent // how do you check whether adjacent with a color? // with adjacent you have to find color efficiently // if you store (color, vertex) pair in a set, then you can find the adjacents quickly // you also have to update them // SQRT Decomp? but its N * sqrt(N) * log(N)? // Light -> B * log(N) + (N / B), heavy -> N / B + log(N) print(); exit(0-0); }
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