【蓝桥-2017国赛】4.分考场

回溯

#include <iostream>

using namespace std;
const int N = 110;
int n, m;
bool a[N][N]; //关系
int p[N][N]; //第N个考场的第几个座位坐的是谁
int minRoom = N;

void dfs(int person, int roomCount){
  if(roomCount >= minRoom) return;
  if(person > n){
    minRoom = min(minRoom, roomCount);
    return;
  }


  for(int i = 1; i <= roomCount; i++){
    int seat = 1;
    while(p[i][seat] && !a[person][p[i][seat]]){
      seat++;
    }

    if(!p[i][seat]){
      p[i][seat] = person;
      dfs(person + 1, roomCount);
      p[i][seat] = 0;
    }
  }
  p[roomCount+1][1] = person;
  dfs(person+1, roomCount+1);
  p[roomCount+1][1] = 0;
};

int main()
{
  cin >> n >> m;
  for(int i = 0; i < m; i++){
    int p1, p2;
    scanf("%d%d", &p1, &p2);
    a[p1][p2] = a[p2][p1] = true;
  }
  dfs(1, 1);
  cout << minRoom;
  return 0;
}