hdu 1162 Eddy's picture

原题链接：http://acm.hdu.edu.cn/showproblem.php?pid=1162
最小生成树。。

#include<algorithm>#include<iostream>#include<cstdlib>#include<cstring>#include<cstdio>#include<vector>#include<queue>#include<cmath>#include<map>using std::map;using std::min;using std::find;using std::sqrt;using std::vector;using std::multimap;using std::priority_queue;#define pb(e) push_back(e)#define sz(c) (int)(c).size()#define mp(a, b) make_pair(a, b)#define all(c) (c).begin(), (c).end()#define iter(c) __typeof((c).begin())#define cls(arr, val) memset(arr, val, sizeof(arr))#define cpresent(c, e) (find(all(c), (e)) != (c).end())#define rep(i, n) for(int i = 0; i < (int)n; i++)#define tr(c, i) for(iter(c) i = (c).begin(); i != (c).end(); ++i)const int N = 110;const int INF = 0x3f3f3f3f;struct P {    double x, y;    P(double i = 0.0, double j = 0.0) :x(i), y(j) {}    double calc(const P &t) const {        return sqrt((x - t.x) * (x - t.x) + (y - t.y) * (y - t.y));    }}A[N];struct edge { int to; double w; int next; }G[(N * N) << 1];struct PII {    int v;    double w;    PII(int i = 0, double j = 0.0) :v(i), w(j) {}    inline bool operator<(const PII &x) const {        return w > x.w;    }};struct Prim {    bool vis[N];    int tot, head[N];    double mincost[N];    inline void init() {        tot = 0, cls(head, -1), cls(vis, false), cls(mincost, 0x3f);    }    inline void add_edge(int u, int v, double w) {        G[tot] = (edge){ v, w, head[u] }; head[u] = tot++;    }    inline void built(int m) {        rep(i, m) {            scanf("%lf %lf", &A[i].x, &A[i].y);        }        for(int i = 0; i < m; i++) {            for(int j = 0; j < m; j++) {                if(i == j) continue;                add_edge(i + 1, j + 1, A[i].calc(A[j]));            }        }    }    inline void prim(int s) {        double ans = 0.0;        priority_queue<PII> q;        q.push(PII(s, 0.0));        for(int i = head[s]; ~i; i = G[i].next) {            mincost[G[i].to] = G[i].w;            q.push(PII(G[i].to, G[i].w));        }        mincost[s] = 0, vis[s] = true;        while(!q.empty()) {            PII t = q.top(); q.pop();            int u = t.v;            if(vis[u]) continue;            vis[u] = true;            ans += t.w;            for(int i = head[u]; ~i; i = G[i].next) {                double &d = mincost[G[i].to];                if(d > G[i].w && !vis[G[i].to]) {                    d = G[i].w;                    q.push(PII(G[i].to, d));                }            }        }        printf("%.2lf\n", ans);    }    inline void solve(int n) {        init(), built(n), prim(1);    }}go;int main() {#ifdef LOCAL    freopen("in.txt", "r", stdin);    freopen("out.txt", "w+", stdout);#endif    int n;    while(~scanf("%d", &n)) {        go.solve(n);    }    return 0;}