結果
| 問題 |
No.19 ステージの選択
|
| ユーザー |
 mai
|
| 提出日時 | 2017-09-24 21:38:37 |
| 言語 | C++17(gcc12) (gcc 12.3.0 + boost 1.87.0) |
| 結果 |
WA
|
| 実行時間 | - |
| コード長 | 7,489 bytes |
| コンパイル時間 | 14,786 ms |
| コンパイル使用メモリ | 290,916 KB |
| 最終ジャッジ日時 | 2025-01-05 03:00:57 |
|
ジャッジサーバーID （参考情報） |
judge5 / judge3 |
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| ファイルパターン | 結果 |
|---|---|
| other | AC * 12 WA * 12 |
ソースコード
#pragma GCC optimize ("O3")
#pragma GCC target ("avx")
#include "bits/stdc++.h" // define macro "/D__MAI"
using namespace std;
typedef long long int ll;
#define xprintf(fmt,...) fprintf(stderr,fmt,__VA_ARGS__)
#define debugv(v) {printf("L%d %s > ",__LINE__,#v);for(auto e:v){cout<<e<<" ";}cout<<endl;}
#define debuga(m,w) {printf("L%d %s > ",__LINE__,#m);for(int x=0;x<(w);x++){cout<<(m)[x]<<" ";}cout<<endl;}
#define debugaa(m,h,w) {printf("L%d %s >\n",__LINE__,#m);for(int y=0;y<(h);y++){for(int x=0;x<(w);x++){cout<<(m)[y][x]<<" ";}cout<<endl;}}
#define ALL(v) (v).begin(),(v).end()
#define repeat(cnt,l) for(auto cnt=0ll;cnt<(l);++cnt)
#define iterate(cnt,b,e) for(auto cnt=(b);cnt!=(e);++cnt)
#define MD 1000000007ll
#define PI 3.1415926535897932384626433832795
#define EPS 1e-12
template<typename T1, typename T2> ostream& operator <<(ostream &o, const pair<T1, T2> p) { o << "(" << p.first << ":" << p.second << ")"; return o; }
template<typename iterator> inline size_t argmin(iterator begin, iterator end) { return distance(begin, min_element(begin, end)); }
template<typename iterator> inline size_t argmax(iterator begin, iterator end) { return distance(begin, max_element(begin, end)); }
template<typename T> T& maxset(T& to, const T& val) { return to = max(to, val); }
template<typename T> T& minset(T& to, const T& val) { return to = min(to, val); }
mt19937_64 randdev(8901016);
inline ll rand_range(ll l, ll h) {
return uniform_int_distribution<ll>(l, h)(randdev);
}
#ifdef __MAI
#define getchar_unlocked getchar
#define putchar_unlocked putchar
#endif
#ifdef __VSCC
#define getchar_unlocked _getchar_nolock
#define putchar_unlocked _putchar_nolock
#endif
namespace {
#define isvisiblechar(c) (0x21<=(c)&&(c)<=0x7E)
class MaiScanner {
public:
template<typename T> void input_integer(T& var) {
var = 0;
T sign = 1;
int cc = getchar_unlocked();
for (; cc<'0' || '9'<cc; cc = getchar_unlocked())
if (cc == '-') sign = -1;
for (; '0' <= cc&&cc <= '9'; cc = getchar_unlocked())
var = (var << 3) + (var << 1) + cc - '0';
var = var*sign;
}
inline int c() { return getchar_unlocked(); }
inline MaiScanner& operator>>(int& var) {
input_integer<int>(var);
return *this;
}
inline MaiScanner& operator>>(long long& var) {
input_integer<long long>(var);
return *this;
}
inline MaiScanner& operator>>(string& var) {
int cc = getchar_unlocked();
for (; !isvisiblechar(cc); cc = getchar_unlocked());
for (; isvisiblechar(cc); cc = getchar_unlocked())
var.push_back(cc);
return *this;
}
template<typename IT> void in(IT begin, IT end) {
for (auto it = begin; it != end; ++it) *this >> *it;
}
};
}
MaiScanner scanner;
class unionfind {
public:
vector<int> data;
unionfind(int size) : data(size, -1) { }
bool union_set(int x, int y) {
x = root(x); y = root(y);
if (x != y) {
if (data[y] < data[x]) swap(x, y);
data[x] += data[y]; data[y] = x;
}
return x != y;
}
inline bool find_set(int x, int y) {
return root(x) == root(y);
}
inline int root(int x) {
return data[x] < 0 ? x : data[x] = root(data[x]);
}
inline int size(int x) {
return -data[root(x)];
}
};
class DGraph {
public:
size_t n;
vector<vector<int>> vertex_to;
vector<vector<int>> vertex_from;
DGraph(size_t n) :n(n), vertex_to(n), vertex_from(n) {}
void connect(int from, int to) {
vertex_to[from].emplace_back(to);
vertex_from[to].emplace_back(from);
}
void resize(size_t _n) {
n = _n;
vertex_to.resize(_n);
vertex_from.resize(_n);
}
};
int strongly_connected_components(const DGraph& graph, unionfind& result) {
stack<int> s;
int size = graph.n;
vector<int> num(size), low(size);
vector<int> flg(size);
int count = 0;
int n_components = graph.n;
function<void(int)> dfs = [&](int idx) {
low[idx] = num[idx] = ++count;
s.push(idx);
flg[idx] = true;
for (int w : graph.vertex_to[idx]) {
if (num[w] == 0) {
dfs(w);
low[idx] = min(low[idx], low[w]);
}
else if (flg[w]) { // ?
low[idx] = min(low[idx], num[w]);
}
}
if (low[idx] == num[idx]) {
while (!s.empty()) {
int w = s.top(); s.pop();
flg[w] = false;
if (idx == w) break;
n_components -= result.union_set(idx, w);
}
}
};
for (int i = 0; i < graph.n; ++i) {
if (num[i] == 0) dfs(i);
}
return n_components;
}
class scc_DGraph {
public:
const DGraph& orig;
DGraph sccg;
vector<int> ori2scc;
vector<vector<int>> scc2ori;
scc_DGraph(const DGraph& g) :orig(g), sccg(1), ori2scc(g.n, -1) { build(); }
void build() {
unionfind uf(orig.n);
strongly_connected_components(orig, uf);
int n_vtx = 0;
for (int i = 0; i < orig.n; ++i) {
int r = uf.root(i);
if (ori2scc[r] == -1) {
ori2scc[r] = n_vtx++;
scc2ori.emplace_back();
}
ori2scc[i] = ori2scc[r];
scc2ori[ori2scc[i]].push_back(i);
}
sccg.resize(n_vtx);
for (int i = 0; i < orig.n; ++i) {
for (int to : orig.vertex_to[i]) {
if (ori2scc[i] == ori2scc[to]) continue;
sccg.connect(ori2scc[i], ori2scc[to]);
}
}
}
inline const vector<int>& vertex_to(int v) const { return sccg.vertex_to[v]; }
inline const vector<int>& vertex_from(int v) const { return sccg.vertex_from[v]; }
inline int size() const { return sccg.n; }
};
ll m, n, kei;
pair<int, int> stages[110];
int main() {
scanner >> n;
DGraph graph(n);
repeat(i, n) {
int l, s;
scanner >> l >> s;
l *= 2;
--s;
stages[i] = make_pair(l, s);
if (s != i) {
graph.connect(s, i);
}
}
scc_DGraph scc(graph);
// 強連結成分の難易度は，「強連結成分の難易度の総和/2 + 強連結成分内の最も簡単な難易度/2」
// 制約(入次数が高々1)より，強連結成分は弱連結成分でもある
// つまり，弱連結成分は，サイクルか根付き木のどちらか．
// もしかして，サイクル検出だけで十分？SCC要らない？
int result = 0;
for (auto& lis : scc.scc2ori) {
if (lis.size() >= 2) {
int easy = 1e9;
int sum = 0;
for (int u : lis) {
int d = stages[u].first;
sum += d;
minset(easy, d);
}
result += sum / 2 + easy / 2;
}
else if (lis.size() == 1) {
int u = lis[0];
int d = stages[u].first;
if (graph.vertex_from[u].size() == 0) { // 入次数が0
result += d;
}
else {
result += d / 2;
}
}
}
cout << ((double)result) / 2 << endl;
return 0;
}