poj 2377 Bad Cowtractors

来源：互联网发布：中控考勤机软件编辑：程序博客网时间：2024/05/17 17:56
原题链接：http://poj.org/problem?id=2377
最大生成树，注意不连通的情况。。
#include<algorithm>#include<iostream>#include<cstdlib>#include<cstring>#include<cstdio>#include<vector>#include<map>using std::map;using std::min;using std::sort;using std::pair;using std::vector;using std::multimap;#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 = 1100;const int INF = 0x3f3f3f3f;struct Kruskal {    struct edge {        int u, v, w;        inline bool operator<(const edge &x) const {            return w > x.w;        }    }G[N * 20];    int E, par[N], rank[N];    inline void init(int n) {        E = 0;        rep(i, n + 1) {            par[i] = i;            rank[i] = 0;        }    }    inline int find(int x) {        while(x != par[x]) {            x = par[x] = par[par[x]];        }        return x;    }    inline bool unite(int x, int y) {        x = find(x), y = find(y);        if(x == y) return false;        if(rank[x] < rank[y]) {            par[x] = y;        } else {            par[y] = x;            rank[x] += rank[x] == rank[y];        }        return true;    }    inline void built(int m) {        int u, v, w;        while(m--) {            scanf("%d %d %d", &u, &v, &w);            G[E++] = (edge){ u, v, w };        }        sort(G, G + E);    }    inline void kruskal(int n) {        bool f = false;        int ans = 0, cnt = 0;;        rep(i, E) {            int u = G[i].u, v = G[i].v;            if(unite(u, v)) {                ans += G[i].w;                if(++cnt >= n - 1) { f = true; break; }            }        }        printf("%d\n", f ? ans : -1);    }    inline void solve(int n, int m) {        init(n), built(m), kruskal(n);    }}go;int main() {#ifdef LOCAL    freopen("in.txt", "r", stdin);    freopen("out.txt", "w+", stdout);#endif    int n, m;    while(~scanf("%d %d", &n, &m)) {        go.solve(n, m);    }    return 0;}
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