畅通工程 HDU

两个模板：

kruskal

#include<stdio.h>
#include<queue>
#include<algorithm>
#include<iostream>
using namespace std;
const int maxn = 105;
int f[maxn];
int find(int x) {
    if (f[x] == x)return x;
    else return(f[x] = find(f[x]));
}
bool same(int x, int y) {
    return (find(x) == find(y));
}
void un(int x, int y) {
    int u = find(x);
    int v = find(y);
    if (u == v)return;
    f[u] = v;
}
struct edge {
    int from, to;
    long long w;
}e[maxn];
bool cmp(edge a, edge b) {
    return a.w < b.w;
}
int main() {
    int n, m;
    while (cin >> m >> n) {
        if (m == 0)break;
        for (int i = 0; i < m; i++) {
            //int x, y, z;
            cin >> e[i].from >> e[i].to >> e[i].w;
        }
        for (int i = 1; i <= n; i++)f[i] = i;
        sort(e, e + m, cmp);
        int res = 0;
        for (int i = 0; i < m; i++) {
            if (same(e[i].from, e[i].to)) continue;
            res += e[i].w;
            un(e[i].from, e[i].to);
        }
        for (int i = 1; i <= n; i++) {
            if (!same(i, 1))res = -1;
        }
        if (res == -1)cout << '?' << endl;
        else cout << res<<endl;
    }
}

prim

#include<stdio.h>
#include<queue>
#include<algorithm>
#include<iostream>
#include<vector>
using namespace std;
const int maxn = 105;
struct edge {
    int to;
    long long w;
    edge(int to = 0, long long w = 0) :to(to), w(w) {}
    bool operator<(const edge &a)const {
        return w > a.w;
    }
};
vector<edge> E[maxn];
bool vis[maxn];
priority_queue<edge> Q;

long long prim() {
    long long ret = 0;
    vis[1] = 1;
    int sz = E[1].size(); for (int i = 0; i < sz; i++) Q.push(E[1][i]);
    while (!Q.empty()) {
        edge t = Q.top(); Q.pop();
        if (vis[t.to])continue;
        ret += t.w; vis[t.to] = 1;    
        int sz = E[t.to].size(); for (int i = 0; i < sz; i++) Q.push(E[t.to][i]);
    }
    return ret;
}


int main() {
    int m, n;
    while (cin >> m >> n) {
        if (m == 0)break;
        for (int i = 0; i <= n; i++)E[i].clear(),vis[i]=0;
        while (!Q.empty()) Q.pop();
        for (int i = 0; i < m; i++) {
            int a, b, c;
            cin >> a >> b >> c;
            E[a].push_back(edge(b, c));
            E[b].push_back(edge(a, c));
        }
        int res = prim();
        for (int i = 1; i <= n; i++) if (!vis[i]) res = -1;
        if (res == -1)cout << '?' << endl;
        else cout << res << endl;
        
    }
}