7-4 天梯地图 (30 分)

7-4 天梯地图 (30 分)

本题要求你实现一个天梯赛专属在线地图,队员输入自己学校所在地和赛场地点后,该地图应该推荐两条路线:一条是最快到达路线;一条是最短距离的路线。题目保证对任意的查询请求,地图上都至少存在一条可达路线。

输入格式:

输入在第一行给出两个正整数N(2 ≤ N ≤ 500)和M,分别为地图中所有标记地点的个数和连接地点的道路条数。随后M行,每行按如下格式给出一条道路的信息:

V1 V2 one-way length time

其中V1V2是道路的两个端点的编号(从0到N-1);如果该道路是从V1V2的单行线,则one-way为1,否则为0;length是道路的长度;time是通过该路所需要的时间。最后给出一对起点和终点的编号。

输出格式:

首先按下列格式输出最快到达的时间T和用节点编号表示的路线:

Time = T: 起点 => 节点1 => ... => 终点

然后在下一行按下列格式输出最短距离D和用节点编号表示的路线:

Distance = D: 起点 => 节点1 => ... => 终点

如果最快到达路线不唯一,则输出几条最快路线中最短的那条,题目保证这条路线是唯一的。而如果最短距离的路线不唯一,则输出途径节点数最少的那条,题目保证这条路线是唯一的。

如果这两条路线是完全一样的,则按下列格式输出:

Time = T; Distance = D: 起点 => 节点1 => ... => 终点

输入样例1:

10 15
0 1 0 1 1
8 0 0 1 1
4 8 1 1 1
5 4 0 2 3
5 9 1 1 4
0 6 0 1 1
7 3 1 1 2
8 3 1 1 2
2 5 0 2 2
2 1 1 1 1
1 5 0 1 3
1 4 0 1 1
9 7 1 1 3
3 1 0 2 5
6 3 1 2 1
5 3

输出样例1:

Time = 6: 5 => 4 => 8 => 3
Distance = 3: 5 => 1 => 3

输入样例2:

7 9
0 4 1 1 1
1 6 1 3 1
2 6 1 1 1
2 5 1 2 2
3 0 0 1 1
3 1 1 3 1
3 2 1 2 1
4 5 0 2 2
6 5 1 2 1
3 5

输出样例2:

Time = 3; Distance = 4: 3 => 2 => 5
#include <iostream>
#include <algorithm>
#include <cstdio>
#include <map>
#include <set>
#include <vector>
#include <cstring>
#include <queue>
#include <cmath>
#define FRER() freopen("in.txt","r",stdin);
#define FREW() freopen("out.txt","w",stdout);
#define mem(a,b) memset(a,b,sizeof(a));
#define go int T;scanf("%d",&T);for(int cas=1;cas<=T;cas++)
#define mod 1000000007
using namespace std;
typedef pair<int,int> pii;
typedef long long ll;
const int maxn = 1000000 + 7 , inf = 0x3f3f3f3f;
int nEdge,n,m,k,st,ed,sumT,sumW,resW,resT;
int totT,totW;
int head[maxn],nxt[maxn],to[maxn],t[maxn],w[maxn];
bool vis[maxn];
int d[maxn];
vector<int>prv1[maxn];
vector<int>prv2[maxn];
vector<int>path1;
vector<int>path2;
vector<int>_path;
void addEdge(int u,int v,int time,int weight){
    to[nEdge] = v;
    nxt[nEdge] = head[u];
    t[nEdge] = time;
    w[nEdge] = weight;
    head[u] = nEdge++;
}
int gt[507][507];
int gw[507][507];
void dij(int c[],vector<int>prv[]){
    for(int i=0;i<=n;i++) d[i] = inf;
    d[st] = 0;
    memset(vis, 0, sizeof(vis));
    priority_queue<pii,vector<pii>,greater<pii> >q;
    q.push(pii(d[st],st));
    while(!q.empty()){
        pii p = q.top();q.pop();
        int u = p.second;
        if(vis[u]) continue;
        vis[u] = 1;
        for(int e = head[u];~e;e=nxt[e]){
            int v = to[e];
            int cost = c[e];
            if(d[v]>d[u]+cost){
                d[v] = d[u]+cost;
                prv[v].clear();
                prv[v].push_back(u);
                q.push(pii(d[v],v));
            }
            else if(d[v]==d[u]+cost){
                prv[v].push_back(u);
            }
        }
    }
}
void dfs1(int u){
    if(u==st){
        if(resW>sumW){
            resW = sumW;
            path1 = _path;
        }
        return;
    }
    for(int i=0;i<prv1[u].size();i++){
        int v = prv1[u][i];
        _path.push_back(v);
        sumW+=gw[u][v];
        dfs1(v);
        sumW-=gw[u][v];
        _path.erase(_path.end()-1);
    }
}
void dfs2(int u){
    if(u==st){
        if(resT>sumT){
            resT = sumT;
            path2 = _path;
        }
        return;
    }
    for(int i=0;i<prv2[u].size();i++){
        int v = prv2[u][i];
        _path.push_back(v);
        sumT++;
        dfs2(v);
        sumT--;
        _path.erase(_path.end()-1);
    }
}
int main(){
    ios::sync_with_stdio(false);
    cin>>n>>m;
    nEdge = sumT = sumW = 0;
    resT = resW = inf;
    for(int i=0;i<=n;i++) head[i] = -1;
    for(int i=1;i<=m;i++){
        int u,v,tag,time,weight;
        cin>>u>>v>>tag>>weight>>time;
        if(!tag){
            addEdge(u, v, time, weight);
            addEdge(v, u, time, weight);
        }else addEdge(u, v, time, weight);
        gt[u][v] = gt[v][u] = time;
        gw[u][v] = gw[v][u] = weight;
    }
    cin>>st>>ed;
    
    dij(t,prv1);
    totT = d[ed];
    
    dij(w,prv2);
    totW = d[ed];
    
    _path.clear();
    _path.push_back(ed);
    dfs1(ed);
    
    _path.clear();
    _path.push_back(ed);
    dfs2(ed);
    
    if(path1==path2){
        printf("Time = %d; Distance = %d: %d",totT,totW,st);
        for(int i = (int)path1.size()-2;i>=0;i--)
            printf(" => %d",path1[i]);
        printf("\n");
    }else{
        printf("Time = %d: %d",totT,st);
        for(int i = (int)path1.size()-2;i>=0;i--)
            printf(" => %d",path1[i]);
        printf("\n");
        printf("Distance = %d: %d",totW,st);
        for(int i = (int)path2.size()-2;i>=0;i--)
            printf(" => %d",path2[i]);
        printf("\n");
    }
}

 

posted @ 2018-11-20 17:37  dslybyme7  阅读(426)  评论(0编辑  收藏  举报