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graph class
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template<typename T> struct Edge | |
{ | |
int src, dst; T w; | |
Edge() {}; | |
Edge(int src, int dst): src(src), dst(dst) {w=1;} | |
Edge(int src, int dst, T w): src(src), dst(dst), w(w){} | |
bool operator<(const Edge &e)const{return w != e.w ? w > e.w : (src != e.src ? src < e.src : dst < e.dst);} | |
bool operator==(const Edge &e){return src == e.src && dst == e.dst;} | |
}; | |
template<typename T> class Graph : public vector<vector<Edge<T>>> | |
{ | |
private: | |
pair<T,int> farthest(int p, int v) | |
{ | |
pair<T,int> r(0,v); | |
for(auto e : (*this)[v]) if(e.dst != p) | |
{ | |
auto t = farthest(v,e.dst); | |
t.first += e.w; | |
if(t.first > r.first) r=t; | |
} | |
return r; | |
} | |
void backward(Graph &h, int v, int s, int r, | |
vector<int> &no, vector<vector<int>> &cmp, | |
vector<int> &prev, vector<vector<int>> &next, vector<T> &mcost, | |
vector<int> &mark, T &cost, bool &found) | |
{ | |
const int n = h.size(); | |
if(mark[v]) | |
{ | |
vector<int> tmp = no; | |
found = true; | |
do { | |
cost += mcost[v]; | |
v = prev[v]; | |
if (v != s) | |
{ | |
while (cmp[v].size() > 0) | |
{ | |
no[cmp[v].back()] = s; | |
cmp[s].push_back(cmp[v].back()); | |
cmp[v].pop_back(); | |
} | |
} | |
} while (v != s); | |
for(auto j : cmp[s]) if(j!=r) for(int l=0;l<h[j].size();l++) | |
if(no[h[j][l].src]!=s) h[j][l].w -= mcost[tmp[j]]; | |
} | |
mark[v] = true; | |
for(auto i : next[v]) if(no[i]!=no[v]&&prev[no[i]]==v) | |
if (!mark[no[i]]||i==s) | |
backward(h,i,s,r,no,cmp,prev,next,mcost,mark,cost,found); | |
} | |
void subaps(int current, int prev, int &timer, | |
vector<bool> &visited, vector<int> &prenum, | |
vector<int> &parent, vector<int> &lowest) | |
{ | |
prenum[current]=lowest[current]=timer++; | |
visited[current]=true; | |
for(auto e : (*this)[current]) | |
{ | |
int next = e.dst; | |
if(!visited[next]) | |
{ | |
parent[next]=current; | |
subaps(next,current,timer,visited,prenum,parent,lowest); | |
lowest[current]=min(lowest[current],lowest[next]); | |
} | |
else if(next != prev) | |
lowest[current]=min(lowest[current],prenum[next]); | |
} | |
} | |
void subbrs(int current, int prev, int &timer, | |
vector<int>&prenum, vector<int>&lowest, set<Edge<T>>&bridges) | |
{ | |
prenum[current]=lowest[current]=timer++; | |
for(auto e : (*this)[current]) if(e.dst!=prev) | |
{ | |
if(prenum[e.dst]==-1) | |
{ | |
subbrs(e.dst,current,timer,prenum,lowest,bridges); | |
lowest[current]=min(lowest[current],lowest[e.dst]); | |
if(prenum[current] < lowest[e.dst]) | |
bridges.insert(Edge<T>(min(e.dst,e.src),max(e.dst,e.src))); | |
} | |
lowest[current]=min(lowest[current],prenum[e.dst]); | |
} | |
} | |
public: | |
T inf; | |
Graph(int n){(*this).resize(n);inf=numeric_limits<T>::max();} | |
void direct(int s, int t){(*this)[s].push_back(Edge<T>(s,t));} | |
void direct(int s, int t, T w){(*this)[s].push_back(Edge<T>(s,t,w));} | |
void undirect(int s, int t){direct(s,t);direct(t,s);} | |
void undirect(int s, int t, T w){direct(s,t,w);direct(t,s,w);} | |
/* | |
cost : O(|V|) | |
*/ | |
T diameter(void) | |
{ | |
auto r = farthest(-1,0); | |
auto t = farthest(-1,r.second); | |
return t.first; | |
} | |
/* | |
s : start point | |
cost : O(|E|+|V|log(|V|)) | |
dist : distances | |
*/ | |
vector<T> dijkstra(int s = 0) | |
{ | |
const int n = (*this).size(); | |
priority_queue<Edge<T>> PQ; | |
vector<T> dist(n,inf); | |
dist[s] = 0; Edge<T> e(-1,s,0); | |
PQ.push(e); | |
while(!PQ.empty()) | |
{ | |
auto f = PQ.top(); PQ.pop(); | |
int u = f.dst; | |
if(dist[u] < f.w * (-1)) continue; | |
for(int j=0;j<(*this)[u].size();j++) | |
{ | |
int v = (*this)[u][j].dst; | |
if(dist[v] > dist[u] + (*this)[u][j].w) | |
{ | |
dist[v] = dist[u] + (*this)[u][j].w; | |
Edge<T> e(-1,v,dist[v]*(-1)); | |
PQ.push(e); | |
} | |
} | |
} | |
return dist; | |
} | |
/* | |
s : start point | |
cost : O(|V||E|) | |
first : is negative cycle ? | |
second : distances | |
*/ | |
pair<bool,vector<T>> bellmanFord(int s = 0) | |
{ | |
const int n = (*this).size(); | |
vector<T> dist(n,inf); | |
dist[s] = 0; | |
for(int i=0;i<n;i++) | |
{ | |
bool update = false; | |
for(int v=0;v<n;v++) for(auto e : (*this)[v]) | |
{ | |
if (dist[v] != inf && dist[e.dst] > dist[v] + e.w) | |
{ | |
dist[e.dst] = dist[v] + e.w; | |
update = true; | |
if(i==n-1) return make_pair(true,dist); | |
} | |
} | |
if(!update) break; | |
} | |
return make_pair(false,dist); | |
} | |
/* | |
Minimum Spanning Tree (Prim's algorithm) | |
r : root | |
cost : O(|E|+|V|log|V|) (because priority_queue use paring sort) | |
first : total cost | |
second : edges | |
*/ | |
pair<T, vector<Edge<T>>> MST(int r = 0) | |
{ | |
const int n = (*this).size(); | |
vector<Edge<T>> U; | |
T total = 0; | |
vector<bool> visited(n,false); | |
priority_queue<Edge<T>> Q; | |
Q.push(Edge<T>(-1,r,0)); | |
while (!Q.empty()) | |
{ | |
auto e = Q.top(); Q.pop(); | |
if (visited[e.dst]) continue; | |
U.push_back(e); | |
total += e.w; | |
visited[e.dst] = true; | |
for(auto f : (*this)[e.dst]) if (!visited[f.dst]) Q.push(f); | |
} | |
return make_pair(total, U); | |
} | |
/* | |
Minimum Spanning Arborescence(Chu-Liu/Edmond) | |
r : root | |
cost : O(|V||E|) | |
*/ | |
T MSA(int r = 0) { | |
const int n = (*this).size(); | |
Graph<T> h(n); | |
for(int i=0;i<n;i++) for(auto e : (*this)[i]) h[e.dst].push_back(e); | |
vector<int> no(n); | |
vector< vector<int> > cmp(n); | |
for(int i=0;i<n;i++) cmp[i].push_back(no[i]=i); | |
for (T cost=0;;) | |
{ | |
vector<int> prev(n,-1); | |
vector<T> mcost(n,inf); | |
for(int j=0;j<n;j++) if(j!=r) for(auto e : h[j]) | |
if (no[e.src] != no[j]) | |
if (e.w < mcost[no[j]]) | |
mcost[no[j]] = e.w, prev[no[j]] = no[e.src]; | |
vector<vector<int>> next(n); | |
for(int i=0;i<n;i++) if(prev[i]>=0) | |
next[prev[i]].push_back(i); | |
bool stop = true; | |
vector<int> mark(n); | |
for(int i=0;i<n;i++) if(i!=r&&!mark[i]&&!cmp[i].empty()) | |
{ | |
bool found = false; | |
backward(h, i, i, r, no, cmp, prev, next, mcost, mark, cost, found); | |
if (found) stop = false; | |
} | |
if (stop) | |
{ | |
for(int i=0;i<n;i++) if(prev[i] >= 0) cost+=mcost[i]; | |
return cost; | |
} | |
} | |
} | |
/* | |
articulation points | |
costs O(|E|log|V|) | |
*/ | |
set<int> APs(void) | |
{ | |
const int n = (*this).size(); | |
set<int> ap; | |
if(n==1) return ap; | |
int timer = 1; | |
vector<bool> visited(n,false); | |
vector<int> prenum(n), parent(n), lowest(n); | |
subaps(0,-1,timer,visited,prenum,parent,lowest); | |
int np = 0; | |
for(int i=1; i<n; i++) | |
{ | |
int p = parent[i]; | |
if(p==0) np++; | |
else if(prenum[p]<=lowest[i]) ap.insert(p); | |
} | |
if(np > 1) ap.insert(0); | |
return ap; | |
} | |
/* | |
bridges | |
only undirect graph | |
*/ | |
set<Edge<T>> bridges(void) | |
{ | |
const int n = (*this).size(); | |
set<Edge<T>> bridges; | |
vector<int> prenum(n,-1), lowest(n,inf); | |
int timer = 0; | |
for(int i=0;i<n;i++) if(prenum[i]==-1) | |
subbrs(i,-1,timer,prenum,lowest,bridges); | |
return bridges; | |
} | |
}; |
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