hdu2263Heavy Cargo

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <queue>//POJ2263
#include <map>
#include <vector>
#include <cstring>
using namespace std;
const int maxn = 210;
const int maxm = 20000;
int n; int r;
int start, dest; //记录节点编号。
bool vis[maxn];//mark each point;//出队列后标记已经被更新过，如果在此访问不可更新其值则不再入队。
int value[maxn];//保存每个节点当前最大值，初始化为-1；  //及时在更新

struct edge {
    int from;
    int to;
    int weight;
};

struct point {
    int num; //  队列里面到节点编号。
    int w;   // 队列里面到，到达此节点到距离。
    bool operator < (const point& b) const {
        return w < b.w;
    }
};

vector<edge> G[maxn];
map<string, int> mymap;
priority_queue<point> Q;

int work()
{
    edge tmp;
    point tmp_point;
    int Size = G[start].size();
    for(int i = 0; i < Size; i++)  { //初始化队列。
        tmp = G[start][i];
        tmp_point.num = tmp.to;
        tmp_point.w = tmp.weight;
        Q.push(tmp_point);
        value[tmp.to] = tmp.weight;//init value;
       // printf("value[%d] = %d
", tmp.to, tmp.weight);
    }
    while(!Q.empty())
    {
        tmp_point = Q.top();
     //   printf("tmp_point.num = %d, tmp_point.w = %d
", tmp_point.num, tmp_point.w);
        Q.pop();
        int len = G[tmp_point.num].size();
        for(int i = 0; i < len; i++) {
            edge edge_tmp = G[tmp_point.num][i];
            if(vis[edge_tmp.to]) { //已经被访问过，只是关心有可能得到解到，并入队。
                if(value[edge_tmp.to] < min(edge_tmp.weight, tmp_point.w)) {
                    value[edge_tmp.to] = min(edge_tmp.weight, tmp_point.w);
                    point p;
                    p.num = edge_tmp.to;
                    p.w = value[edge_tmp.to];
                    Q.push(p);
                }
            }
            else {//未被访问过。
                value[edge_tmp.to] = min(edge_tmp.weight, value[edge_tmp.from]);
                point p;
                p.num = edge_tmp.to;
                p.w = value[edge_tmp.to];
                Q.push(p);
            }
        }
        vis[tmp_point.num] = true;
        if(tmp_point.num == dest) return tmp_point.w;//get result;
    }
    return value[n];
}

void init() {
    while(!Q.empty()) Q.pop();
    mymap.clear();
    memset(vis, false, sizeof(vis));
    for(int i = 0; i <= n; i++) {
        value[i] = -1;
    }
}

int main()
{
    int counter = 1;
    while(scanf("%d%d", &n, &r)!=EOF) {
        init();
        int cnt = 1; // 给节点编号。
        if(n==0 && r==0) break;
        string tmp[2];
        int weight;
        edge t; //临时变量
        map<string, int>::iterator it;
        for(int i = 1; i <= r; i++) {
                cin >> tmp[0];
                cin >> tmp[1];
                for(int i = 0; i < 2; i++) {
                    if(mymap.find(tmp[i])==mymap.end())
                        mymap[tmp[i]] = cnt++;
                }
                cin >> weight;
                t.from = mymap[tmp[0]];
                t.to = mymap[tmp[1]];
                t.weight = weight;
                G[t.from].push_back(t);
                t.from = mymap[tmp[1]];
                t.to = mymap[tmp[0]];
                G[t.from].push_back(t);
        }
        cin >> tmp[0] >> tmp[1];
        start = mymap[tmp[0]], dest = mymap[tmp[1]];
        int res = work();
        printf("Scenario #%d
", counter++);
        printf("%d tons

", res);
    }
    return 0;
}