【HDOJ】3832 Earth Hour

其实就是bfs，不过也可以写成最短路，因为权重为1，可以用Spira解。

/* 3832 */
#include <iostream>
#include <string>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <vector>
#include <deque>
#include <algorithm>
#include <cstdio>
#include <cmath>
#include <ctime>
#include <cstring>
#include <climits>
#include <cctype>
#include <cassert>
#include <functional>
#include <iterator>
#include <iomanip>
using namespace std;
//#pragma comment(linker,"/STACK:102400000,1024000")

#define sti                set<int>
#define stpii            set<pair<int, int> >
#define mpii            map<int,int>
#define vi                vector<int>
#define pii                pair<int,int>
#define vpii            vector<pair<int,int> >
#define rep(i, a, n)     for (int i=a;i<n;++i)
#define per(i, a, n)     for (int i=n-1;i>=a;--i)
#define clr                clear
#define pb                 push_back
#define mp                 make_pair
#define fir                first
#define sec                second
#define all(x)             (x).begin(),(x).end()
#define SZ(x)             ((int)(x).size())
#define lson            l, mid, rt<<1
#define rson            mid+1, r, rt<<1|1

const int maxn = 205;
const int maxe = maxn*maxn*2;
const int INF = 1e7;
int X[maxn], Y[maxn], R[maxn];
int dis[maxn], D[3][maxn];
bool inS[maxn];
int V[maxe], nxt[maxe];
int head[maxn], head_[maxn], n, m;

void addEdge(int u, int v) {
    V[m] = v;
    nxt[m] = head[u];
    head[u] = m++;
    
    V[m] = u;
    nxt[m] = head[v];
    head[v] = m++;
}

typedef struct node_t {
    int u, v, w;
    
    node_t() {}
    
    node_t(int u_, int v_, int w_):
        u(u_), v(v_), w(w_) {}
        
    friend bool operator< (const node_t& a, const node_t& b) {
        return a.w > b.w;
    }
} node_t;

void forward(priority_queue<node_t>& Q, int u) {
    int& k = head_[u];
    
    if (k != -1) {
        Q.push(node_t(u, V[k], dis[u]+1));
        k = nxt[k];
    }
}

void Spira(int s) {
    priority_queue<node_t> Q;
    node_t nd;
    int cnt = 1;
    
    memset(inS, false, sizeof(inS));
    rep(i, 1, n+1)    dis[i] = INF;
    dis[s] = 0;
    inS[s] = true;
    forward(Q, s);
    
    while (!Q.empty()) {
        nd = Q.top();
        Q.pop();
        forward(Q, nd.u);
        if (!inS[nd.v]) {
            inS[nd.v] = true;
            dis[nd.v] = nd.w;
            if (++cnt == n)
                break;
            forward(Q, nd.v);
        }
    }
}

int main() {
    ios::sync_with_stdio(false);
    #ifndef ONLINE_JUDGE
        freopen("data.in", "r", stdin);
        freopen("data.out", "w", stdout);
    #endif
    
    int t;
    int mn, ans;
    
    scanf("%d", &t);
    while (t--) {
        scanf("%d", &n);
        rep(i, 1, n+1)
            scanf("%d %d %d", &X[i], &Y[i], &R[i]);
        memset(head, -1, sizeof(head));
        m = 0;
        rep(i, 1, n+1) {
            rep(j, 1, i) {
                if ((X[i]-X[j])*(X[i]-X[j])+(Y[i]-Y[j])*(Y[i]-Y[j]) <= (R[i]+R[j])*(R[i]+R[j])) {
                    addEdge(i, j);
                }
            }
        }
        
        memcpy(head_, head, sizeof(head));
        Spira(1);
        memcpy(D[0], dis, sizeof(dis));
        
        memcpy(head_, head, sizeof(head));
        Spira(2);
        memcpy(D[1], dis, sizeof(dis));
        
        memcpy(head_, head, sizeof(head));
        Spira(3);
        memcpy(D[2], dis, sizeof(dis));
        
        mn = INF;
        rep(i, 1, n+1)
            mn = min(mn, D[0][i]+D[1][i]+D[2][i]);
            
        ans = (mn==INF) ? -1:n-mn-1;
        printf("%d
", ans);
    }
    
    #ifndef ONLINE_JUDGE
        printf("time = %d.
", (int)clock());
    #endif
    
    return 0;
}