最大生成树+map实现技巧

POJ2263

 //#include<bits/stdc++.h>
 #include<iostream>
 #include<cstdio>
 #include<algorithm>
 #include<vector>
 #include<cstring>
 #include<map>
 #include<set>
 #include<queue>
 #include<bitset>
 #include<utility>
 #include<functional>
 #include<iomanip>
 #include<sstream>
 #include<ctime>
 #include<cassert>
 #define fi first
 #define se second
 #define mp make_pair
 #define pb push_back
 #define pw(x) (1ll << (x))
 #define sz(x) ((int)(x).size())
 #define all(x) (x).begin(),(x).end()
 #define rep(i,l,r) for(int i=(l);i<(r);i++)
 #define per(i,r,l) for(int i=(r);i>=(l);i--)
 #define FOR(i,l,r) for(int i=(l);i<=(r);i++)
 #define debug1(a)       cout << #a << " = " << a << endl;
 #define debug2(a,b)     cout << #a << " = " << a << endl;\
     cout << #b << " = " << b << endl;
 #define debug3(a,b,c)   cout << #a << " = " << a << endl;\
     cout << #b << " = " << b << endl;\
     cout << #c << " = " << c << endl;
 #define debug4(a,b,c,d)\
     cout << #a << " = " << a << endl;\
     cout << #b << " = " << b << endl;\
     cout << #c << " = " << c << endl;\
     cout << #d << " = " << d << endl;
 #define eps 1e-9
 #define PIE acos(-1)
 #define cl(a,b) memset(a,b,sizeof(a))
 #define fastio ios::sync_with_stdio(false);cin.tie(0);
 #define lson l , mid , ls
 #define rson mid + 1 , r , rs
 #define ls (rt<<1)
 #define rs (ls|1)
 #define INF 0x3f3f3f3f
 #define lowbit(x) (x&(-x))
 #define sqr(a) a*a
 #pragma GCC optimize(2)
 using namespace std;
 typedef double db;
 typedef long long ll;
 typedef vector<int> vi;
 typedef pair<int, int> pii;

 const int maxn=2e5;
 int u[maxn],v[maxn],w[maxn],p[maxn],r[maxn];
 int n,m,cnt;
 map<string,int>MAP;

 int cmp(const int i,const int j){return w[i]>w[j];}
 int find(int x){return p[x]==x?x:p[x]=find(p[x]);}
 int kruscal(int t1,int t2)
 {
     int ans=;
     rep(i,,maxn)p[i]=r[i]=i;
     sort(r,r+m,cmp);
     rep(i,,m){
         int e=r[i];
         int x=find(u[e]);
         int y=find(v[e]);
         if(x!=y){
             p[x]=y;
             if(find(t1)==find(t2)){
                 ans=w[e];
                 return ans;
             }
         }
     }
     return w[r[m]];
 }
 void Init()
 {
     MAP.clear();
     cnt=;
 }
 int main()
 {
     int cas=;
     while(cin>>n>>m,n&&m){
         Init();
         char s1[],s2[];
         rep(i,,m){
             scanf("%s%s%d",s1,s2,&w[i]);
             if(!MAP.count(s1))MAP[s1]=cnt++;
             if(!MAP.count(s2))MAP[s2]=cnt++;
             u[i]=MAP[s1];
             v[i]=MAP[s2];
 //            debug3(MAP[s1],MAP[s2],w[i]);
         }
         scanf("%s%s",s1,s2);
         printf("Scenario #%d\n", ++cas);
         printf("%d tons\n\n", kruscal(MAP[s1],MAP[s2]));
 //        printf("Scenario #%d\n%d tons\n\n",++cas,kruscal(MAP[s1],MAP[s2]));
     }
     return ;
 }