제출 #659648

#제출 시각아이디문제언어결과실행 시간메모리
659648LoboStar Trek (CEOI20_startrek)C++17
0 / 100
21 ms35668 KiB
#include<bits/stdc++.h> using namespace std; const long long inf = (long long) 1e18 + 10; const int inf1 = (int) 1e9 + 10; #define int long long #define dbl long double #define endl '\n' #define sc second #define fr first #define mp make_pair #define pb push_back #define all(x) x.begin(), x.end() const int maxn = 5e5+10; const int mod = 1e9+7; int n, d, dpw[maxn][2], dpl[maxn][2], dpwup[maxn][2], dplup[maxn][2]; vector<int> g[maxn]; int SL, SW, SL0, SW0, SWb, SLb; void dfs1(int u, int ant) { dpw[u][1] = SW*dpw[u][0] + SL*(dpw[u][0]+dpl[u][0]); dpw[u][1]%= mod; dpl[u][1] = SW*dpl[u][0]; dpl[u][1]%= mod; int qtl = 0; for(auto v : g[u]) if(v != ant) { qtl+= dpl[v][0]; dfs1(v,u); } for(auto v : g[u]) if(v != ant) { qtl-= dpl[v][0]; if(qtl) { dpw[u][1]+= dpw[v][1]+dpl[v][1]; dpw[u][1]%= mod; dpl[u][1]+= 0; } else { dpw[u][1]+= dpl[v][1]; dpw[u][1]%= mod; dpl[u][1]+= dpw[v][1]; dpl[u][1]%= mod; } qtl+= dpl[v][0]; } } int dw[maxn][2], dl[maxn][2], sdw[maxn][2], sdl[maxn][2], sbsz[maxn]; set<int> dl0s[maxn]; void calc(int u) { if(sdl[u][0] >= 1) { dw[u][0] = 1; } else { dw[u][0] = 0; } if(sdl[u][0] >= 2) { dw[u][1] = 1+sdw[u][1]+sdl[u][1]; } else if(sdl[u][0] == 1) { dw[u][1] = 1+sdw[u][1]+sdl[u][1]; int v1 = *dl0s[u].begin(); dw[u][1]-= dw[v1][1]; } else { dw[u][1] = 1+sdl[u][1]; } dl[u][0] = 1-dw[u][0]; dl[u][1] = sbsz[u]-dw[u][1]; } void sol(int u, int ant) { dw[u][0] = 0; dl[u][0] = 0; sdw[u][0] = 0; sdl[u][0] = 0; dw[u][1] = 0; dl[u][1] = 0; sdw[u][1] = 0; sdl[u][1] = 0; sbsz[u] = 1; dl0s[u].clear(); for(auto v : g[u]) if(v != ant) { sol(v,u); sdw[u][0]+= dw[v][0]; sdw[u][1]+= dw[v][1]; sdl[u][0]+= dl[v][0]; sdl[u][1]+= dl[v][1]; sbsz[u]+= sbsz[v]; if(dl[v][0]) { dl0s[u].insert(v); } } calc(u); } void dfsrrt(int u, int ant) { SWb+= dw[u][1]; for(auto v : g[u]) if(v != ant) { // take v off u sdw[u][0]-= dw[v][0]; sdw[u][1]-= dw[v][1]; sdl[u][0]-= dl[v][0]; sdl[u][1]-= dl[v][1]; sbsz[u]-= sbsz[v]; if(dl[v][0]) { dl0s[u].erase(v); } calc(u); // put u into v sdw[v][0]+= dw[u][0]; sdw[v][1]+= dw[u][1]; sdl[v][0]+= dl[u][0]; sdl[v][1]+= dl[u][1]; sbsz[v]+= sbsz[u]; if(dl[u][0]) { dl0s[v].insert(u); } calc(v); dfsrrt(v,u); // take u off v sdw[v][0]-= dw[u][0]; sdw[v][1]-= dw[u][1]; sdl[v][0]-= dl[u][0]; sdl[v][1]-= dl[u][1]; sbsz[v]-= sbsz[u]; if(dl[u][0]) { dl0s[v].erase(u); } calc(v); // put v into u sdw[u][0]+= dw[v][0]; sdw[u][1]+= dw[v][1]; sdl[u][0]+= dl[v][0]; sdl[u][1]+= dl[v][1]; sbsz[u]+= sbsz[v]; if(dl[v][0]) { dl0s[u].insert(v); } calc(u); } } void dfs0(int u, int ant) { dpw[u][0] = 0; int qtl = 0; for(auto v : g[u]) if(v != ant) { dfs0(v,u); qtl+= dpl[v][0]; } if(qtl) dpw[u][0] = 1; dpl[u][0] = 1-dpw[u][0]; } void dfs0up(int u, int ant) { int qtl = 0; for(auto v : g[u]) if(v != ant) { qtl+= dpl[v][0]; } for(auto v : g[u]) if(v != ant) { qtl-= dpl[v][0]; if(qtl || dpwup[u][0]) { dpwup[v][0] = 0; dplup[v][0] = 1-dpwup[v][0]; } else { dpwup[v][0] = 1; dplup[v][0] = 1-dpwup[v][0]; } qtl+= dpl[v][0]; } for(auto v : g[u]) if(v != ant) { dfs0up(v,u); } } void solve() { cin >> n >> d; for(int i = 1; i <= n-1; i++) { int u,v; cin >> u >> v; g[u].pb(v); g[v].pb(u); } dfs0(1,0); dpwup[1][0] = 0; dplup[1][0] = 1; dfs0up(1,0); for(int i = 1; i <= n; i++) { if(dpw[i][0] || dpwup[i][0]) SW0++; else SL0++; } sol(1,0); dfsrrt(1,0); // for(int i = 1; i <= n; i++) { // sol(i,0); // SWb+= dw[i][1]; // // cout << i << " " << dw[i][1] << endl; // } SLb = n*n-SWb; // cout << SWb << " " << SLb << endl; // cout << SW0 << " " << SL0 << endl; SWb%= mod; SLb%= mod; SW = SW0; SL = SL0; for(int i = 1; i <= d-1; i++) { int newSW = n*(SW*SW0%mod)%mod + SL*SWb; newSW%= mod; int newSL = n*(SW*SL0%mod)%mod + SL*SLb; newSL%= mod; SW = newSW; SL = newSL; } dfs1(1,0); // cout << SW << " " << SL << endl; cout << dpw[1][1] << endl; } int32_t main() { ios::sync_with_stdio(false); cin.tie(0); freopen("in.in", "r", stdin); // freopen("out.out", "w", stdout); int tt = 1; // cin >> tt; while(tt--) { solve(); } }

컴파일 시 표준 에러 (stderr) 메시지

startrek.cpp: In function 'int32_t main()':
startrek.cpp:229:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  229 |     freopen("in.in", "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~
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