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=0;
    rep(i,0,maxn)p[i]=r[i]=i;
    sort(r,r+m,cmp);
    rep(i,0,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=0;
}
int main()
{
    int cas=0;
    while(cin>>n>>m,n&&m){
        Init();
        char s1[50],s2[50];
        rep(i,0,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
", ++cas);
        printf("%d tons

", kruscal(MAP[s1],MAP[s2]));
//        printf("Scenario #%d
%d tons

",++cas,kruscal(MAP[s1],MAP[s2]));
    }
    return 0;
}