Time Limit: 1000MS | Memory Limit: 30000K | |
Total Submissions: 4269 | Accepted: 2004 |
Description
Input
Output
Sample Input
0 0 1 0 3 3 (0,1) (0,2) (1,2) 2 0 5 7 (0,1) (0,2) (1,3) (1,2) (1,4) (2,3) (3,4)
Sample Output
0 1 3 0 2
Hint
//POJ1966
#include
#include
#include
#include
#define MAXN 100+10
#define MAXM 20000+10
#define INF 0x3f3f3f3f
using namespace std;
struct Edge
{
int from, to, cap, flow, next;
};
Edge edge[MAXM], Redge[MAXM];
int head[MAXN], Rhead[MAXN], edgenum;
int N, M;
int dist[MAXN], cur[MAXN];
bool vis[MAXN];
void init()
{
edgenum = 0;
memset(head, -1, sizeof(head));
}
void addEdge(int u, int v, int w)
{
for(int i = head[u]; i != -1; i = edge[i].next)
{
if(edge[i].to == v)
return ;
}
Edge E1 = {u, v, w, 0, head[u]};
edge[edgenum] = E1;
head[u] = edgenum++;
Edge E2 = {v, u, 0, 0, head[v]};
edge[edgenum] = E2;
head[v] = edgenum++;
}
int a[MAXM], b[MAXM];
void input()
{
for(int i = 0; i < M; i++)
scanf(" (%d,%d)", &a[i], &b[i]), a[i]++, b[i]++;
}
void getMap(int s, int t)
{
init();
for(int i = 0; i < M; i++)
{
addEdge(a[i]+N, b[i], INF);
addEdge(b[i]+N, a[i], INF);
}
for(int k = 1; k <= N; k++)
(k != s && k != t) ? addEdge(k, k+N, 1) : addEdge(k, k+N, INF);
}
bool BFS(int s, int t)
{
queue Q;
memset(dist, -1, sizeof(dist));
memset(vis, false, sizeof(vis));
dist[s] = 0; vis[s] = true;
Q.push(s);
while(!Q.empty())
{
int u = Q.front();
Q.pop();
for(int i = head[u]; i != -1; i = edge[i].next)
{
Edge E = edge[i];
if(!vis[E.to] && E.cap > E.flow)
{
dist[E.to] = dist[u] + 1;
if(E.to == t) return true;
vis[E.to] = true;
Q.push(E.to);
}
}
}
return false;
}
int DFS(int x, int a, int t)
{
if(x == t || a == 0) return a;
int flow = 0, f;
for(int &i = cur[x]; i != -1; i = edge[i].next)
{
Edge &E = edge[i];
if(dist[E.to] == dist[x] + 1 && (f = DFS(E.to, min(a, E.cap-E.flow), t)) > 0)
{
edge[i].flow += f;
edge[i^1].flow -= f;
flow += f;
a -= f;
if(a == 0) break;
}
}
return flow;
}
int Maxflow(int s, int t)
{
int flow = 0;
while(BFS(s, t))
{
memcpy(cur, head, sizeof(head));
flow += DFS(s, INF, t);
}
return flow;
}
void solve()
{
int ans = N;
for(int i = 1; i <= N; i++)//枚举源点
{
for(int j = i+1; j <= N; j++)//汇点
{
getMap(i, j);
ans = min(ans, Maxflow(i, j));//更新
}
}
printf("%d\n", ans);
}
int main()
{
while(scanf("%d%d", &N, &M) != EOF)
{
input();
solve();
}
return 0;
}