[图的DFS遍历]--犯罪团伙的头目和成员人数

题目来源：PAT A1034

#include <bits/stdc++.h>
using namespace std;
const int maxn = 2010;        //最大顶点数
int n, k;                     //n次通话,通话总时长的阈值为k
map<int, string> intToString; //编号--姓名
map<string, int> stringToInt; //姓名--编号
map<string, int> Gang;        //head--人数
int G[maxn][maxn];
int weight[maxn];         //点权
int numPerson;            //总人数
bool vis[maxn] = {false}; //标记是否被访问

//DFS函数访问单个连通块(目的是获取每个连通块的头目--连通块内点权最大的结点)，nowVisit为当前访问的编号
//head为头目编号,numMember为成员人数,totalValue为连通块的总边权
void DFS(int nowVisit, int &head, int &numMember, int &totalValue)
{
    numMember++;
    vis[nowVisit] = true;
    if (weight[nowVisit] > weight[head])
    {
        head = nowVisit; //更新头目
    }
    for (int i = 0; i < numPerson; i++)
    {
        if (G[nowVisit][i] > 0)
        {
            totalValue += G[nowVisit][i];
            G[nowVisit][i] = G[i][nowVisit] = 0;
            if (vis[i] == false)
            {
                DFS(i, head, numMember, totalValue);
            }
        }
    }
}

void DFSTrave() //遍历图G
{
    for (int i = 0; i < numPerson; i++)
    {
        if (vis[i] == false)
        {
            int head = i;
            int numMember = 0;
            int totalValue = 0;
            DFS(i, head, numMember, totalValue);
            if (numMember > 2 && totalValue > k)
            {
                Gang[intToString[head]] = numMember;
            }
        }
    }
}

//返回姓名str对应的编号
int change(string str)
{
    if (stringToInt.find(str) != stringToInt.end())
    {
        return stringToInt[str];
    }
    else
    {
        stringToInt[str] = numPerson;
        intToString[numPerson] = str;
        return numPerson++;
    }
}

int main()
{
    cin >> n >> k;
    int w;
    string str1, str2;
    for (int i = 0; i < n; i++)
    {
        cin >> str1 >> str2 >> w;
        int id1 = change(str1);
        int id2 = change(str2);
        weight[id1] += w;
        weight[id2] += w;
        G[id1][id2] += w;
        G[id2][id1] += w;
    }
    DFSTrave();
    cout << Gang.size() << endl;
    map<string, int>::iterator it;
    for (it = Gang.begin(); it != Gang.end(); it++)
    {
        cout << it->first << ' ' << it->second << endl;
    }
    return 0;
}