OJ-Problems-Source/HDOJ/2444_autoAC.cpp
2016-08-22 00:16:58 +08:00

78 lines
1.6 KiB
C++

#include <stdio.h>
#include <string.h>
bool map[210][210];
bool visit[210];
int link[210];
int judge[210];
int queue[210];
int n,m;
bool BFS()
{
int v,start = 0,end = 1;
queue[0] = 1;
for(int i=0;i<=n;i++)
judge[i] = -1;
v = queue[start];
judge[1] = 0;
memset(visit,0,sizeof(visit));
while(start<end)
{
v= queue[start];
for(int i = 1;i <= n; i++)
{
if(map[v][i]){
if(judge[i] == -1){
judge[i] = (judge[v]+1)%2;
queue[end++] = i;
}
else{
if(judge[i] == judge[v])
return false;
}
}
}
start++;
}
return true;
}
int can(int r)
{
for(int i=1;i<=n;i++)
{
if(map[r][i] && visit[i] == 0){
visit[i] = 1;
if(link[i]==0 || can(link[i])){
link[i] = r;
return 1;
}
}
}
return 0;
}
int main()
{
while(scanf("%d%d",&n,&m)!=EOF)
{
memset(map,0,sizeof(map));
int a,b;
for(int i=0;i<m;i++)
{
scanf("%d%d",&a,&b);
map[a][b] = 1;
map[b][a] = 1;
}
if(!BFS()) {
printf("No\n");continue;
}
int num = 0;
memset(link,0,sizeof(link));
for(int i=1;i<=n;i++)
{
memset(visit,0,sizeof(visit));
if(can(i)) num++;
}
printf("%d\n",num/2);
}
return 0;
}