Oil Skimming HDU - 4185
匈牙利
#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;
char mp[660][660];
int g[660][660];
int relate[660][660];
int match[660];
int vis[660];
int k,n;
int tmp;
int dfs(int u){
int i;
for(i = 0; i < tmp; i++){
if(g[u][i] && !vis[i]){
vis[i] = 1;
if(!match[i] || dfs(match[i])){
match[i] = u;
return 1;
}
}
}
return 0;
}
int hungry(){
int i;
int cnt = 0;
memset(match,0,sizeof(match));
for(i = 0; i < tmp; i++){
memset(vis,0,sizeof(vis));
if(dfs(i))
cnt++;
}
return cnt;
}
int main(){
cin >> k;
int cas = 0;
while(k--){
cin >> n;
getchar();
memset(relate,0,sizeof(relate));
memset(g,0,sizeof(g));
int i,j;
tmp = 0;
for(i = 0; i < n; i++){
cin >> mp[i];
getchar();
for(j = 0; j < n; j++){
if(mp[i][j] == '#')
relate[i][j] = tmp++;
}
}
for(i = 0; i < n; i++){
for(j = 0; j < n; j++){
if(mp[i][j] != '#') continue;
if(mp[i-1][j] == '#') g[relate[i][j]][relate[i-1][j]] = 1;
if(mp[i+1][j] == '#') g[relate[i][j]][relate[i+1][j]] = 1;
if(mp[i][j-1] == '#') g[relate[i][j]][relate[i][j-1]] = 1;
if(mp[i][j+1] == '#') g[relate[i][j]][relate[i][j+1]] = 1;
}
}
int ans = hungry();
printf("Case %d: %d\n",++cas,ans/2);//除以2是因为每个点都作为起点看了一遍,即正反都看了一遍所以是真正答案的两倍
}
return 0;
}
HK
#include<cstdio>
#include<queue>
#include<cstring>
using namespace std;
typedef long long ll;
const int N=600*600+10;
const int M=600*600*2+10;
const int INF=0x7f7f7f7f;
const int DX[]={0,0,-1,1};
const int DY[]={-1,1,0,0};
int e[M],ne[M],h[M],idx;
void addedge(int a,int b)
{
e[idx]=b;
ne[idx]=h[a];
h[a]=idx++;
}
void init()
{
idx=0;
memset(h,-1,sizeof(h));
}
int uN;
int Mx[N],My[N];
int dx[N],dy[N];
int dis;
bool used[N];
bool SearchP()
{
queue<int> q;
memset(dx,-1,sizeof(dx));
memset(dy,-1,sizeof(dy));
for(int i=1;i<=uN;i++)
if(Mx[i]==-1)
{
q.push(i);
dx[i]=0;
}
dis=INF;
while(!q.empty())
{
int u=q.front();
q.pop();
if(dx[u]>dis) break;
for(int i=h[u];i!=-1;i=ne[i])
{
int v=e[i];
if(dy[v]==-1)
{
dy[v]=dx[u]+1;
if(My[v]==-1) dis=dy[v];
else
{
dx[My[v]]=dy[v]+1;
q.push(My[v]);
}
}
}
}
return dis!=INF;
}
bool dfs(int u)
{
for(int i=h[u];i!=-1;i=ne[i])
{
int v=e[i];
if(!used[v]&&dy[v]==dx[u]+1)
{
used[v]=true;
if(My[v]!=-1&&dy[v]==dis) continue;
if(My[v]==-1||dfs(My[v]))
{
My[v]=u;
Mx[u]=v;
return true;
}
}
}
return false;
}
int MaxMatch()
{
int res=0;
memset(Mx,-1,sizeof(Mx));
memset(My,-1,sizeof(My));
while(SearchP())
{
memset(used,false,sizeof(used));
for(int i=1;i<=uN;i++)
if(Mx[i]==-1&&dfs(i)) res++;
}
return res;
}
char g[610][610];
int id[610][610];
int main()
{
int n,T,kase=0;
scanf("%d",&T);
while(T--)
{
init();
scanf("%d",&n);
for(int i=1;i<=n;i++)
scanf("%s",g[i]+1);
memset(id,-1,sizeof(id));
int cnt=1;
for(int i=1;i<=n;i++)
for(int j=1;j<=n;j++)
if(g[i][j]=='#'&&(i+j)%2==0)
id[i][j]=cnt++;
uN=cnt-1;
for(int i=1;i<=n;i++)
for(int j=1;j<=n;j++)
if(g[i][j]=='#'&&(i+j)%2==1)
{
int t=cnt++;
for(int k=0;k<4;k++)
{
int ni=i+DX[k];
int nj=j+DY[k];
if(id[ni][nj]!=-1) addedge(id[ni][nj],t);
}
}
printf("Case %d: %d\n",++kase,MaxMatch());
}
return 0;
}