HDU 2389 Rain on your Parade（Hopcroft_Carp Algorithm）

#include <cstdio>
#include <cstring>
#include <cmath>
#include <iostream>
#include <string>
#include <algorithm>
#include <climits>
#include <queue>
using namespace std;
const int MAX_N = 3010;

int T, n, m, total, dis, cases = 0;
double t, x[MAX_N], y[MAX_N], v[MAX_N];
int matchx[MAX_N], matchy[MAX_N], head[MAX_N];
int disx[MAX_N],disy[MAX_N], vis[MAX_N];

struct Edge{
int to, next;

Edge () {}
Edge(int _to, int _next) : to(_to), next(_next) {
}
}edge[MAX_N*MAX_N];

inline void init()
{
total=0;
memset(matchx,-1,sizeof(matchx));
memset(matchy,-1,sizeof(matchy));
memset(head,-1,sizeof(head));
}

inline void AddEdge(int from, int to)
{
edge[total].to = to;
edge[total].next = head[from];
head[from] = total++;
}

inline bool bfs()
{
dis = INT_MAX;
memset(disx, -1, sizeof(disx));
memset(disy, -1, sizeof(disy));
queue<int> que;
for(int i = 0; i < n; i++){
if(matchx[i] == -1){
que.push(i);
disx[i] = 0;
}
}
while(!que.empty()){
int u = que.front();
que.pop();
if( disx[u] > dis) break;
for(int i = head[u]; i != -1; i = edge[i].next){
int v = edge[i].to;
if( disy[v] == -1){
disy[v] = disx[u] + 1;
if(matchy[v] == -1) dis = disy[v];
else {
disx[matchy[v]] = disy[v] + 1;
que.push(matchy[v]);
}
}
}
}
return dis != INT_MAX;
}

inline bool dfs(int u)
{
for(int i = head[u]; i != -1; i = edge[i].next){
int v = edge[i].to;
if(!vis[v]){
vis[v] = 1;
if(matchy[v] != -1 && disy[v] == dis) continue;
if(matchy[v] == -1 || dfs(matchy[v]) ){
matchy[v] = u;
matchx[u] = v;
return true;
}
}
}
return false;
}

inline int Hopcroft_Carp()
{
int ans = 0;
while( bfs() ){
memset(vis, 0, sizeof(vis));
for(int i = 0; i < n; i++){
if(matchx[i] == -1 && dfs(i)) ans++;
}
}
return ans;
}

int main()
{
freopen("hdu2389.in","r",stdin);
scanf("%d", &T);
while(T-- > 0){
init();
scanf("%lf%d", &t, &n);
for(int i = 0; i < n; i++){
scanf("%lf%lf%lf",&x[i], &y[i], &v[i]);
}
scanf("%d",&m);
for(int i = 0; i < m; i++){
double tmpx, tmpy;
scanf("%lf%lf",&tmpx, &tmpy);
for(int j = 0; j < n; j++){
double tmp = sqrt((tmpx - x[j]) * (tmpx - x[j]) + (tmpy - y[j]) * (tmpy - y[j]));
if(v[j] * t >= tmp){
//printf("j = %d i = %d\n",j, i);
AddEdge(j,i);
}
}
}
int ans = Hopcroft_Carp();
printf("Scenario #%d:\n%d\n\n",++cases,ans);
}
return 0;
}