2112HDU Today(SPFA)

刚开始用spfa(久闻大名却一次都没用过)过不了,改dijkstra,wa了十几次后,心灰意冷。。1个小时后终于发现是判断起点与终点相同时,直接continue了,导致后面的数据没有完全输入...改正这个问题后spfa的代码也过了,哈哈

#include <iostream>
#include <algorithm>
#include <cstring>
#include <vector>
#include <string>
#include <map>
#include <queue>
using namespace std;

#ifndef ONLINE_JUDGE
#include <fstream>
ifstream fin("test.txt");
#define cin fin
#endif

struct edge{
    int to,w;
};
const int MAXN = 200,INF = 10000000;
vector <edge> adjmap[MAXN];

bool inq[MAXN];
int d[MAXN],n;
map <string, int> m;
void SPFA()
{
    int i,j;
    memset(inq,0,sizeof(inq));
    queue <int> q;
    for(i = 1; i <= 155; ++i)
    d[i] = INF;
    d[1] = 0;
    inq[1] = 1;
    q.push(1);
    while(!q.empty())
    {
        int t = q.front();
        q.pop();
        inq[t] = 0;
        for(i = 0; i < adjmap[t].size(); ++i)
        {
            int to = adjmap[t][i].to;
            if(d[t] < INF && d[to] > d[t] + adjmap[t][i].w)
            {
                d[to] = d[t] + adjmap[t][i].w;
                if(!inq[to])
                {
                    inq[to] = 1;
                    q.push(to);
                }
            }
        }
    }
}
int main()
{
    ios::sync_with_stdio(false);
    int i,t,num;
    string a,b;

    while(cin >> n)
    {
        if(n == -1)
        break;
        m.clear();
        for(i = 0; i < MAXN; ++i)
        adjmap[i].clear();
        cin >> a >> b;
        int ok = 1;
        if(a == b)
        {
            ok = 0;
        }
        m[a] = 1;     
        m[b] = 2;
        num = 3;
        for(i = 0; i < n; ++i)
        {
            cin >> a >> b >> t;
            if(!m[a])
            m[a] = num++;
            if(!m[b])
            m[b] = num++;
            edge tem;
            tem.to = m[a];
            tem.w = t;
            adjmap[m[b]].push_back(tem);
            tem.to = m[b];
            adjmap[m[a]].push_back(tem);
        }
        if(!ok)
        {
            cout << 0 << endl;
            continue;
        }
        SPFA();
        if(d[2]!=INF)
        cout << d[2] << endl;
        else
        cout << -1 << endl;
    }
    return 0;
}

原文地址:https://www.cnblogs.com/fchx/p/3097586.html