成都赛区网选 HDU 4039 The Social Network（BFS）

给出n个人物关系，p个查询，询问每个人的推荐好友（公共好友最多的且不是好友的人）。

将人物看作点，存在好友关系看作边，则题意转化为查询与某点最短路径长度为2的最多路径的点。

这样直接构图后BFS即可，将深度为2的存进队列查询次数，注意下输出格式和数组的大小，人是有可能超过1000的！

桂副队长的代码，好长。。。

#include<stdio.h>
#include<queue>
#include<iostream>
#include<map>
#include<string>
#include<string.h>
#include<stdlib.h>
using namespace std;

int adjl[3005][3005];

struct Node
{
int temp;
int step;
Node()
{
temp = step = 0;
}
};

int main()
{
int t;
scanf("%d",&t);
int o = 1;
while(t--)
{
memset(adjl , 0 , sizeof(adjl));
int n,q;
scanf("%d%d",&n,&q);
int i,j,k;
string ch , sh;
map<string , int> Map;
map<int , string> reMap;
int Count = 1;
for( i = 0 ; i < n ; i++)
{
cin>>ch>>sh;
if(Map[ch] == 0 )
{
Map[ch] = Count++;
//cout<<ch<<" "<<Count-1<<endl;
reMap[Count-1] = ch;
}
if(Map[sh] == 0)
{
Map[sh] = Count++;
reMap[Count-1] = sh;
//cout<<sh<<" "<<Count-1<<endl;
}
//system("pause");
adjl[Map[ch]][++adjl[Map[ch]][0]] =  Map[sh];
adjl[Map[sh]][++adjl[Map[sh]][0]] =  Map[ch];
}

/*
for( i = 1 ; i <= Count - 1; i++)
cout<<reMap[i]<<" "<<Map[reMap[i]]<<endl;

system("pause");
*/

printf("Case %d:\n",o++);

for( i = 0 ; i < q ; i++)
{
cin>>ch;
Node start;
start.temp = Map[ch];
start.step = 0;
queue<Node> myq;
int Flag[3005] = {0};
myq.push(start);

int num[3005] = {0};

int MAX = 0;

int g[3005] = {0};
int gg = 1;

while(!myq.empty())
{
Node temp = myq.front();
myq.pop();
if(temp.step == 0)
{
for( j = 1 ; j <= adjl[temp.temp][0] ; j++)
{
Flag[adjl[temp.temp][j]] = 1;
Node tt ;
tt.temp = adjl[temp.temp][j];

tt.step = 1;
myq.push(tt);
}
}
else if(temp.step == 1)
{
for( j = 1 ; j <= adjl[temp.temp][0] ; j++)
{

int Adj = adjl[temp.temp][j];
if(Adj != start.temp)
{
if(Flag[Adj] == 0)
{
num[Adj]++;
if(MAX < num[Adj])
{
MAX = num[Adj];
gg = 1;
g[gg++] = Adj;
}
else if(MAX == num[Adj])
{
g[gg++] = Adj;
}
}
}
}
}
else break;
}

//system("pause");

//printf("gg = %d start.temp = %d\n",gg,start.temp);

map<string,int> mm;
for( j = 1 ; j <= gg - 1 ; j++)
{
//cout<<reMap[j]<<endl;
mm[reMap[g[j]]]++;
}
if(MAX == 0)
{
printf("-\n");
}
else
{
map<string,int>::iterator map_m=mm.begin();
cout<<map_m->first;
map_m++;
for(;map_m!=mm.end();map_m++)
{
cout<<" "<<map_m->first;
}
printf("\n");
}
}

}
return 0;
}