#UVa:1197-The Suspects

利用 DFS 檢查從 0 號學生開始可以連到多少學生即可得解。建圖時,每個群組可以將群組裡面的其他學生全部連到群組中的特定學生(例如:第一個學生)即可。

C++(0.000)

/*******************************************************/
/* UVa 1197 The Suspects                               */
/* Author: Maplewing [at] knightzone.org               */
/* Version: 2018/05/17                                 */
/*******************************************************/
#include <iostream>
#include <cstdio>
#include <vector>
using namespace std;

int getDFSNodeCount(const vector<vector<int>> &graph, vector<bool> &isVisited, int startPoint){
  isVisited[startPoint] = true;

  int count = 1;
  for(int i = 0 ; i < graph[startPoint].size() ; ++i){
    if(!isVisited[graph[startPoint][i]]){
      count += getDFSNodeCount(graph, isVisited, graph[startPoint][i]);
    }
  }

  return count;
}

int main(){
  int n, m;
  while(scanf("%d%d", &n, &m) != EOF &&
        (n != 0 || m != 0)){

    vector<vector<int>> studentConnectGraph(n, vector<int>());
    for(int i = 0 ; i < m ; ++i){
      int k;
      scanf("%d", &k);

      int rootStudent = 0;
      for(int j = 0 ; j < k ; ++j){
        int currentStudent;
        scanf("%d", &currentStudent);

        if(j == 0){
          rootStudent = currentStudent;
          continue;
        }
        studentConnectGraph[rootStudent].push_back(currentStudent);
        studentConnectGraph[currentStudent].push_back(rootStudent);
        rootStudent = currentStudent;
      }
    }

    vector<bool> isVisited(n, false);
    printf("%d\n", getDFSNodeCount(studentConnectGraph, isVisited, 0));  
  }
  return 0;
}

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