poj 2472 106 miles to Chicago

因为求安全性最大的路径，所以可以将dist[1]定为-1,再作spfa处理

//poj 2472 106 miles to Chicago/* *  因为求安全性最大的路径，所以可以将dist[1]定为-1,再作spfa处理 * spfa(st) 之后有dist[]得到距离 *///licatweijei#include<iostream>using namespace std;#define INF 1000000#define MAXE 10100#define MAXV 10100#include <queue>#include <cstring>#include <iomanip>double dist[MAXV];deque<int> pqu;bool visited[MAXV];int cnt[MAXV];int last[MAXV];struct edge{    int x,y;    double d;    int next;}edges[MAXE];int len;int first[MAXV];int V; // to be difinevoid init(int v){    memset(cnt,0,sizeof(cnt));    memset(visited,false,sizeof(visited));    memset(first,0,sizeof(first));    memset(last,0,sizeof(last));    len = 0;    V = v;}void add_edge(int x,int y,double d){    ++len;    edges[len].x = x;    edges[len].y = y;    edges[len].d = d;    edges[len].next = first[x];    first[x] = len;}bool spfa(int st){    for (int i=0;i<=V;i++)    {        dist[i] = INF;    }    dist[st] = -1;    visited[st] = true;    pqu.push_front(st);    while(!pqu.empty()){        int now = pqu.front();        pqu.pop_front();        visited[now] = false;        for (int nt = first[now];nt!=0;nt = edges[nt].next){            if (edges[nt].d * dist[now] < dist[edges[nt].y] ) {                dist[edges[nt].y] =  edges[nt].d * dist[now];                last[edges[nt].y] = now;                if (!visited[edges[nt].y]){                    visited[edges[nt].y] = true;                    cnt[edges[nt].y]++;                    if (cnt[edges[nt].y]>V) return false;                    if (!pqu.empty()){                        if (dist[edges[nt].y]>dist[pqu.front()])                            pqu.push_back(edges[nt].y);                        else                            pqu.push_front(edges[nt].y);                    } else pqu.push_front(edges[nt].y);                }            }        }    }    return true;}int main (void){    int n,m;    while(cin >> n ){        if (n==0) break;        cin >> m;        init(n);        int x,y;        double d;        for (int i=0;i<m;i++){            cin >> x >> y >> d;            d/=100;            add_edge(x,y,d);            add_edge(y,x,d);        }        spfa(1);        cout << setiosflags(ios::fixed) << setprecision(6) << -dist[n]*100 << " percent" << endl;    }}