A

PS： 题目就不描述了。。。

铭记：以后要记得好好读题，因为这浪费自己好多时间。

先上错误代码：

#include <cstdio>#include <cstring>#include <cstdlib>#include <algorithm>#include <vector>#include <map>#include <deque>#include <queue>#include <set>#include <iostream>#include <string>#include <fstream>#include <stack>//it's not a binary tree.// So stupid.using namespace std;const int maxn =1e3+10;const int INF=1e6+1;int Map[maxn][maxn];int dist[maxn];int n,m;bool vis[maxn];struct node{     int data;     int next;     node(int x,int y): data(x),next(y){}};struct monde{     int pos,fare;};bool cmp(monde a,monde b){     return a.fare <b.fare;}int result[maxn];void dfs();int main (){    cin>>n;    int i,j,k;    //init//    fill(vis,vis+n,0);    for (i=0;i<n+1;i++)    for (j=0;j<n+1;j++)    Map[i][j]=INF;    string a;    for (i=2;i<=n;i++)    {        for (j=1;j<i;j++)        {            cin>>a;            if(a=="x")            continue;            else            {                 int len =a.size();                int s =0;                 for (k=0;k<len;k++)                 {                    s=s*10+(a[k]-'0');                 }                 Map[i][j]=Map[j][i]=s;            }        }    }//    cout<<endl;    ////right to print//    for (i=1;i<=n;i++)//    {//        for (j=1;j<=n;j++)//        if(Map[i][j]!=INF)//        cout<<Map[i][j]<<"\t";//        else//        cout<<"X\t";//        cout<<endl;//    }     Map[1][1]=0;     dfs();    return 0;}void dfs(){     int maxx=0;     queue<node>q;     int i,j,k;    q.push(node(0,1));    int step=0;    vis[1]=1;    while (!q.empty())    {         ////first node is [1][1];         node e=q.front();         q.pop();//         cout<<endl;//         cout<<e.next<<endl;//         for (i=1;i<=n;i++)//         cout<<vis[i]<<" ";//         cout<<endl;         monde pos[n];        for(i=1;i<=n;i++)        {             pos[i-1].pos=i;             pos[i-1].fare=Map[i][e.next];        }//        cout<<" first"<<endl;//        for (i=0;i<n;i++)//        cout<<pos[i].pos<<" "<<pos[i].fare<<endl;        sort(pos,pos+n,cmp);//        cout<<" second"<<endl;//        for (i=0;i<n;i++)//        cout<<pos[i].pos<<" "<<pos[i].fare<<endl;        int cnt =0;        for (i=0;i<n;i++)        {         if (!vis[pos[i].pos]&&pos[i].fare!=INF)         {             vis[pos[i].pos]=1;             q.push(node(pos[i].fare+e.data,pos[i].pos));             cnt++;             result[step++]=pos[i].fare+e.data;//             cout<<pos[i].pos<<"   "<<pos[i].fare<<endl;         }         if(cnt==2)            break;        }    }//    cout<<endl;    for (i=0;i<step;i++)        if(maxx<result[i])        maxx=result[i];        cout<<maxx<<endl;}

ac 代码：

//#include <bits/stdc++.h>#include <cstdio>#include <cstring>#include <cstdlib>#include <algorithm>#include <vector>#include <map>#include <deque>#include <queue>#include <set>#include <iostream>#include <string>#include <fstream>#include <stack>using namespace std;const int maxn=1e3+1;const int INF=1e6+1;typedef long long ll;int dist[maxn];typedef pair<int,int>pp;struct node{     int to,data;    node(int x,int y): to(x),data(y){}};vector<node>g[maxn];int n,m;///rememeber  : using priority_queue to save time   is a tool/// dist[] is very important.void dijkstra(int st){     fill(dist,dist+n+1,INF);// +n ==[0,n);  +(n+1)  ==[0,n];     /// wa     int i,j,k;     priority_queue<pp,vector<pp>,greater<pp> >q;//     while (!q.empty())//     q.pop();     dist[st]=0;     q.push(pp(0,st)); // 1 is data, 2 is the pos     while (!q.empty())     {         pp p=q.top();         q.pop();         int v=p.second;         /// min         if(p.first>dist[v])         continue;         int l =g[v].size();         for (i=0;i<l;i++)         {            node e =g[v][i];            if(dist[e.to]>dist[v]+e.data)            {                dist[e.to]=dist[v]+e.data;                q.push(pp(dist[e.to],e.to));            }         }     }}int main(){     int i,j,k;     int x,y,z;     cin>>n;    string a;    for (i=2;i<=n;i++)    {        for (j=1;j<i;j++)        {            cin>>a;            if(a=="x")            continue;            else            {                 int len =a.size();                int s =0;                 for (k=0;k<len;k++)                 {                    s=s*10+(a[k]-'0');                 }                 g[i].push_back(node(j,s));                 g[j].push_back(node(i,s));            }        }    }        dijkstra(1);        int maxx =0;        for (i=1;i<=n;i++)        if (maxx<dist[i])        maxx=dist[i];        cout<<maxx<<endl;        ///init        for (i=0;i<n;i++)        g[i].clear();     return 0;}

对于自己犯下的严重错误，罚2公里。。。。。。

我跑步去了。。。。。