PAT (Advanced Level) 1087. All Roads Lead to Rome (30)

Posted 2020-08-02 Fighting Heart

暴力DFS。

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

const int maxn=1000+10;
int n,m;
string st;
map<string ,int>m1;
map<int ,string>m2;
int sz;
int h[maxn];
struct Edge
{
    int u,v,c;
}e[maxn*maxn];
int tot;
vector<int>g[maxn];

int des;
int ans_cost=0x7FFFFFFF;
int ans_count=0;
int ans_happy=0;
int ans_point=0;
int path[maxn],ans_path[maxn];
bool flag[maxn];

void dfs(int x,int cost,int happy,int point)
{
    if(cost>ans_cost) return;
    if(x==des)
    {
        if(cost<ans_cost)
        {
            ans_cost=cost;
            ans_count=1;
            ans_happy=happy;
            ans_point=point;
            for(int i=0;i<point;i++)
                ans_path[i]=path[i];
        }

        else if(cost==ans_cost)
        {
            ans_count++;
            if(happy>ans_happy)
            {
                ans_happy=happy;
                ans_point=point;
                for(int i=0;i<point;i++)
                    ans_path[i]=path[i];
            }

            else if(happy==ans_happy)
            {
                if(point<ans_point)
                {
                    ans_point=point;
                    for(int i=0;i<point;i++)
                        ans_path[i]=path[i];
                }
            }
        }
        return;
    }

    for(int i=0;i<g[x].size();i++)
    {
        int id=g[x][i];
        path[point]=e[id].v;
        if(flag[e[id].v]==1) continue;
        flag[e[id].v]=1;
        dfs(e[id].v,cost+e[id].c,happy+h[e[id].v],point+1);
        flag[e[id].v]=0;
    }
}

int main()
{
    scanf("%d%d",&n,&m); cin>>st;
    m1[st]=++sz; m2[sz]=st;

    for(int i=1;i<=n-1;i++)
    {
        string name; cin>>name;
        m1[name]=++sz; m2[sz]=name;
        int val; scanf("%d",&val);
        h[sz]=val;
    }

    des=m1["ROM"];

    tot=0;
    for(int i=1;i<=m;i++)
    {
        string U,V; int c; cin>>U>>V>>c;
        e[tot++].u=m1[U]; e[tot].v=m1[V]; e[tot].c=c;
        g[m1[U]].push_back(tot);

        e[tot++].u=m1[V]; e[tot].v=m1[U]; e[tot].c=c;
        g[m1[V]].push_back(tot);
    }

    memset(flag,0,sizeof flag);
    flag[1]=1;
    dfs(1,0,0,0);

    printf("%d %d %d %d\n",ans_count,ans_cost,ans_happy,ans_happy/ans_point);

    cout<<st;
    for(int i=0;i<ans_point;i++)
        cout<<"->"<<m2[ans_path[i]];
    printf("\n");

    return 0;
}