OJ-Problems-Source/HDOJ/4687_autoAC.cpp
2016-09-06 13:33:42 +08:00

188 lines
4.2 KiB
C++

#include <stdio.h>
#include <string.h>
#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <string>
#include <math.h>
#include <stdlib.h>
#include <time.h>
using namespace std;
const int MAXN = 50;
int N;
bool Graph[MAXN][MAXN];
int Match[MAXN];
bool InQueue[MAXN],InPath[MAXN],InBlossom[MAXN];
int Head,Tail;
int Queue[MAXN];
int Start,Finish;
int NewBase;
int Father[MAXN],Base[MAXN];
int Count;
void Push(int u)
{
Queue[Tail] = u;
Tail++;
InQueue[u] = true;
}
int Pop()
{
int res = Queue[Head];
Head++;
return res;
}
int FindCommonAncestor(int u,int v)
{
memset(InPath,false,sizeof(InPath));
while(true)
{
u = Base[u];
InPath[u] = true;
if(u == Start) break;
u = Father[Match[u]];
}
while(true)
{
v = Base[v];
if(InPath[v])break;
v = Father[Match[v]];
}
return v;
}
void ResetTrace(int u)
{
int v;
while(Base[u] != NewBase)
{
v = Match[u];
InBlossom[Base[u]] = InBlossom[Base[v]] = true;
u = Father[v];
if(Base[u] != NewBase) Father[u] = v;
}
}
void BloosomContract(int u,int v)
{
NewBase = FindCommonAncestor(u,v);
memset(InBlossom,false,sizeof(InBlossom));
ResetTrace(u);
ResetTrace(v);
if(Base[u] != NewBase) Father[u] = v;
if(Base[v] != NewBase) Father[v] = u;
for(int tu = 1; tu <= N; tu++)
if(InBlossom[Base[tu]])
{
Base[tu] = NewBase;
if(!InQueue[tu]) Push(tu);
}
}
void FindAugmentingPath()
{
memset(InQueue,false,sizeof(InQueue));
memset(Father,0,sizeof(Father));
for(int i = 1;i <= N;i++)
Base[i] = i;
Head = Tail = 1;
Push(Start);
Finish = 0;
while(Head < Tail)
{
int u = Pop();
for(int v = 1; v <= N; v++)
if(Graph[u][v] && (Base[u] != Base[v]) && (Match[u] != v))
{
if((v == Start) || ((Match[v] > 0) && Father[Match[v]] > 0))
BloosomContract(u,v);
else if(Father[v] == 0)
{
Father[v] = u;
if(Match[v] > 0)
Push(Match[v]);
else
{
Finish = v;
return;
}
}
}
}
}
void AugmentPath()
{
int u,v,w;
u = Finish;
while(u > 0)
{
v = Father[u];
w = Match[v];
Match[v] = u;
Match[u] = v;
u = w;
}
}
void Edmonds()
{
memset(Match,0,sizeof(Match));
for(int u = 1; u <= N; u++)
if(Match[u] == 0)
{
Start = u;
FindAugmentingPath();
if(Finish > 0)AugmentPath();
}
}
int getMatch()
{
Edmonds();
Count = 0;
for(int u = 1; u <= N;u++)
if(Match[u] > 0)
Count++;
return Count/2;
}
bool g[MAXN][MAXN];
pair<int,int>p[150];
int main()
{
int m;
while(scanf("%d%d",&N,&m)==2)
{
memset(g,false,sizeof(g));
memset(Graph,false,sizeof(Graph));
int u,v;
for(int i = 1;i <= m;i++)
{
scanf("%d%d",&u,&v);
p[i] = make_pair(u,v);
g[u][v] = true;
g[v][u] = true;
Graph[u][v] = true;
Graph[v][u] = true;
}
int cnt0 = getMatch();
vector<int>ans;
for(int i = 1;i <= m;i++)
{
u = p[i].first;
v = p[i].second;
memcpy(Graph,g,sizeof(g));
for(int j = 1;j <= N;j++)
Graph[j][u] = Graph[u][j] = Graph[j][v] = Graph[v][j] = false;
int cnt = getMatch();
if(cnt < cnt0-1)
ans.push_back(i);
}
int sz = ans.size();
printf("%d\n",sz);
for(int i = 0;i < sz;i++)
{
printf("%d",ans[i]);
if(i < sz-1)printf(" ");
}
printf("\n");
}
return 0;
}