hdu-2112 HDU Today---dijkstra+标号

题目链接：

http://acm.hdu.edu.cn/showproblem.php?pid=2112、

题目大意：

求起点到终点的最短路

解题思路：

对地名进行编号即可

然后直接dijkstra算法

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn = 1000 + 10;
const int INF = 0x3f3f3f3f;
int Map[maxn][maxn];
int v[maxn], d[maxn];
int n, m;
set<string>cnt;
map<string, int>G;
int GetID(string s)
{
    if(cnt.count(s))return G[s];
    cnt.insert(s);
    return G[s] = cnt.size();
}
void dijkstra(int s, int t)
{
    memset(v, 0, sizeof(v));
    for(int i = 0; i <= n; i++)d[i] = (i == s ? 0 : INF);
    for(int i = 0; i < n; i++)
    {
        int x = -1, m = INF;
        for(int i = 1; i <= n; i++)if(!v[i] && d[i] <= m)m = d[x = i];
        v[x] = 1;
        for(int i = 1; i <= n; i++)
        {
            if(d[i] > d[x] + Map[x][i])
            {
                d[i] = d[x] + Map[x][i];
            }
        }
    }
    if(d[t] == INF)d[t] = -1;
    cout<<d[t]<<endl;
}

int main()
{
    while(scanf("%d", &n) != EOF && n != -1)
    {
        int u, v, w;
        string s1,s2;
        cnt.clear();
        G.clear();
        cin >> s1 >> s2;
        int s = GetID(s1);
        int t = GetID(s2);
        memset(Map, INF, sizeof(Map));
        while(n--)
        {
            cin >> s1 >> s2 >> w;
            Map[GetID(s1)][GetID(s2)] = Map[GetID(s2)][GetID(s1)] = min(Map[GetID(s1)][GetID(s2)], w);
        }
        n = cnt.size();
        dijkstra(s, t);
    }
}