poj 1789 Truck History

原题链接：http://poj.org/problem?id=1789
堆优化的Prim最小生成树算法。。

#include<algorithm>#include<iostream>#include<cstdlib>#include<cstring>#include<cstdio>#include<vector>#include<queue>#include<map>using std::map;using std::min;using std::find;using std::pair;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 = 2100;const int INF = 0x3f3f3f3f;struct P {    int w, v;    P(int i = 0, int j = 0) :w(i), v(j) {}    inline bool operator<(const P &x) const {        return w > x.w;    }};struct Prim {    typedef char State[8];    struct edge { int to, w, next; }G[N * N];    State st[N];    bool vis[N];    int tot, head[N], mincost[N];    inline void init() {        tot = 0, cls(vis, false), cls(head, -1), cls(mincost, 0x3f);    }    inline void add_edge(int u, int v, int w) {        G[tot] = (edge){ v, w, head[u] }; head[u] = tot++;    }    inline int calc(int i, int j) {        int res = 0;        rep(k, 7) {            if(st[i][k] != st[j][k]) res++;        }        return res;    }    inline void built(int n) {        rep(i, n) scanf("%s", st[i]);        rep(i, n) {            rep(j, n) {                int ret = calc(i, j);                if(i == j) continue;                add_edge(i + 1, j + 1, ret);            }        }    }    inline void prim(int s) {        int ans = 0;        priority_queue<P> q;        q.push(P(0, s));        for(int i = head[s]; ~i; i = G[i].next) {            mincost[G[i].to] = G[i].w;            q.push(P(G[i].w, G[i].to));        }        mincost[s] = 0, vis[s] = true;        while(!q.empty()) {            P 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) {                int &d = mincost[G[i].to];                if(d > G[i].w && !vis[G[i].to]) {                    d = G[i].w;                    q.push(P(G[i].w, G[i].to));                }            }        }        printf("The highest possible quality is 1/%d.\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), n) {        go.solve(n);    }    return 0;}