544 - Heavy Cargo

最大生成树

#include <iostream>
#include <algorithm>
#include <cstdio>
#include <cstring>
#include <map>
using namespace std;
const int maxn = 100 + 7;
const int maxm = 19900 + 7;
const int INF = ~0U >> 1;
int n, m, kase = 0;
int p[maxn];
struct node {
    int u, v, val;
    bool operator<(const node&r) const {
        return val > r.val;
    }
}str[maxm];
map<string, int> ma;

int Find(int x) { return p[x] == x ? x : p[x] = Find(p[x]); }

int main() {
    while(scanf("%d%d", &n, &m) != EOF && n && m) {
        ma.clear();
        for(int i = 0; i <= n; ++i) p[i] = i;
        char s1[100] = {0}, s2[100] = {0};
        int val, k = 0;
        for(int i = 0; i < m; ++i) {
            scanf("%s%s%d", s1, s2, &val);
            string a(s1), b(s2);
            if(ma.count(a) == 0) ma[a] = k++;
            if(ma.count(b) == 0) ma[b] = k++;
            str[i] = (node){ma[a], ma[b], val};
        }
        scanf("%s%s", s1, s2);
        string a(s1), b(s2);
        int u = ma[a], v = ma[b];
        sort(str, str + m);
        int ans = INF;
        for(int i = 0; i < m; ++i) {
            node e = str[i];
            int x = Find(e.u), y = Find(e.v);
            if(x != y) {
                p[x] = y;
                ans = min(ans, e.val);
            }
            x = Find(u), y = Find(v);
            if(x == y) break;
        }
        printf("Scenario #%d\n", ++kase);
        printf("%d tons\n\n", ans);
    }
    return 0;
}