hdu2389 Rain on your Parade (最大匹配Hopcroft--Karp)

#include <cstdio>
#include <queue>
#include <vector>
#include <cstring>
#include <cmath>
#define MAXN 3002
using namespace std;

struct node
{
int x,y;
}guests[MAXN],umbrella[MAXN];

int nx,ny,distx[MAXN],disty[MAXN];
int visited[MAXN],mx[MAXN],my[MAXN];
vector<int> graphics[MAXN];
queue<int> Q;

int Scan()
{
int res = 0, ch, flag = 0;
if((ch = getchar()) == '-')
flag = 1;
else if(ch >= '0' && ch <= '9')
res = ch - '0';
while((ch = getchar()) >= '0' && ch <= '9' )
res = res * 10 + ch - '0';
return flag ? -res : res;
}

double Cal_Dist(int i,int j)
{
double x=1.0*(guests[i].x-umbrella[j].x);
double y=1.0*(guests[i].y-umbrella[j].y);
return sqrt(x*x+y*y);
}

int find(int u)
{//寻找增广路
int i,temp;
for(i=0;i<graphics[u].size();++i)//枚举所有以i为起点的边
{
temp=graphics[u][i];
if(!visited[temp]&&(disty[temp]==distx[u]+1))
{
visited[temp]=1;
if(!my[temp]||find(my[temp]))
{
mx[u]=temp;
my[temp]=u;
return 1;
}
}
}
return 0;
}

int search()
{
int temp,u,flag=0;
memset(distx,0,sizeof(distx));
memset(disty,0,sizeof(disty));
while(!Q.empty())
Q.pop();
for(int i=1;i<=nx;++i)
{
if(!mx[i])
Q.push(i);
}
while(!Q.empty())
{
u=Q.front();
Q.pop();
for(int i=0;i<graphics[u].size();++i)
{
temp=graphics[u][i];
if(!disty[temp])
{
disty[temp]=distx[u]+1;
if(my[temp])
{
distx[my[temp]]=disty[temp]+1;
Q.push(my[temp]);
}
else
flag=1;
}
}
}
return flag;
}

int matching()
{
int ans=0;
memset(mx,0,sizeof(mx));
memset(my,0,sizeof(my));
while(search())
{
memset(visited,0,sizeof(visited));
for(int i=1;i<=nx;++i)
if(!mx[i]&&find(i))
ans++;
}
return ans;
}

int main()
{
int test,time,i,j,cases=1;
int speed[MAXN];
scanf("%d",&test);
while(test--)
{
scanf("%d %d",&time,&nx);
for(i=1;i<=nx;++i)
{
//scanf("%d %d %d",&guests[i].x,&guests[i].y,&speed[i]);
guests[i].x=Scan();
guests[i].y=Scan();
speed[i]=Scan();
}
//scanf("%d",&ny);
ny=Scan();
for(i=1;i<=ny;++i)
{
//scanf("%d %d",&umbrella[i].x,&umbrella[i].y);
umbrella[i].x=Scan();
umbrella[i].y=Scan();
}
for(i=1;i<=nx;++i)
{//能够在下雨前拿到伞的建一条边
graphics[i].clear();
for(j=1;j<=ny;++j)
if(1.0*speed[i]*time>=Cal_Dist(i,j))
graphics[i].push_back(j);
}
printf("Scenario #%d:\n",cases++);
printf("%d\n\n",matching());
}
return 0;
}

#include <cstdio>
#include <queue>
#include <vector>
#include <cstring>
#define MAXN 3002
#define INF 0x3ffffff
using namespace std;

int guests[MAXN][2],umbrella[MAXN][2];
int nx,ny,dis,distx[MAXN],disty[MAXN];
int visited[MAXN],mx[MAXN],my[MAXN];
int graphics[MAXN][MAXN];
queue<int> Q;

int Scan()
{
int res = 0, ch, flag = 0;
if((ch = getchar()) == '-')
flag = 1;
else if(ch >= '0' && ch <= '9')
res = ch - '0';
while((ch = getchar()) >= '0' && ch <= '9' )
res = res * 10 + ch - '0';
return flag ? -res : res;
}

int search()
{
int u;
dis=INF;
memset(distx,-1,sizeof(distx));
memset(disty,-1,sizeof(disty));
while(!Q.empty())
Q.pop();
for(int i=0;i<nx;++i)
{
if(mx[i]==-1)
{
Q.push(i);
distx[i]=0;
}
}
while(!Q.empty())
{
u=Q.front();
Q.pop();
if(distx[u]>dis)
break;
for(int i=0;i<ny;++i)
{
if(graphics[u][i]&&disty[i]==-1)
{
disty[i]=distx[u]+1;
if(my[i]==-1)
{
dis=disty[i];
}
else
{
distx[my[i]]=disty[i]+1;
Q.push(my[i]);
}
}
}
}
return dis!=INF;
}

int findpath(int u)
{//寻找增广路
for(int i=0;i<ny;++i)
{
if(!visited[i]&&graphics[u][i]&&(disty[i]==distx[u]+1))
{
visited[i]=1;
if(my[i]!=-1&&disty[i]==dis)
continue;
if(my[i]==-1||findpath(my[i]))
{
mx[u]=i;
my[i]=u;
return 1;
}
}
}
return 0;
}

int matching()
{
int ans=0;
memset(mx,-1,sizeof(mx));
memset(my,-1,sizeof(my));
while(search())
{
memset(visited,0,sizeof(visited));
for(int i=0;i<nx;++i)
if(mx[i]==-1&&findpath(i))
ans++;
}
return ans;
}

int main()
{
int test,time,i,j,x,y,temp,cases=1;
int speed[MAXN];
scanf("%d",&test);
while(test--)
{
scanf("%d %d",&time,&nx);
for(i=0;i<nx;++i)
{
scanf("%d %d %d",&guests[i][0],&guests[i][1],&speed[i]);
}
scanf("%d",&ny);
for(i=0;i<ny;++i)
{
scanf("%d %d",&umbrella[i][0],&umbrella[i][1]);
//umbrella[i][0]=Scan();
//umbrella[i][1]=Scan();
}
memset(graphics,0,sizeof(graphics));
for(i=0;i<nx;++i)
{
for(j=0;j<ny;++j)
{
temp=speed[i]*speed[i]*time*time;
x=(guests[i][0]-umbrella[j][0]);
y=(guests[i][1]-umbrella[j][1]);
if(temp>=x*x+y*y)
graphics[i][j]=1;
}
}
printf("Scenario #%d:\n",cases++);
printf("%d\n\n",matching());
}
return 0;
}