CodeForces 242C King's Path(bfs+map)

#include <iostream>
#include <cstdio>
#include <cstring>
#include <map>
#include <queue>
using namespace std;
map<pair<int,int>,int> MAP;            // 存地图
pair<int,int> Now,Next;
int dir[8][2] = {1,0, 0,1, -1,0, 0,-1, 1,1, -1,-1, -1,1, 1,-1};
int S_x,S_y,E_x,E_y,n;

int bfs(){
  queue<pair<int,int> > q;
  Now.first = S_x;
  Now.second = S_y;
  MAP[Now] = 0;
  q.push(Now);
  while(!q.empty()){
    Now = q.front();
    q.pop();
    if(Now.first == E_x && Now.second == E_y){
      return MAP[Now];
    }
    for(int i=0;i<8;i++){
      Next.first = Now.first + dir[i][0];
      Next.second = Now.second +dir[i][1];
      if(MAP.count(Next) && MAP[Next] == -1){         // MAP.count表示判断这个点能不能走，MAP[]判断这个点走没走过
        MAP[Next] = MAP[Now] + 1;
        q.push(Next);
      }
    }
  }
  return -1;
}

int main()
{
  scanf("%d%d%d%d%d",&S_x,&S_y,&E_x,&E_y,&n);
  MAP.clear();
  for(int i=0;i<n;i++){
    int temp,a,b;
    scanf("%d%d%d",&temp,&a,&b);
    for(int i=a;i<=b;i++){
      Now.first = temp;
      Now.second = i;
      MAP[Now] = -1;                       // 用来标记走没走过
    }
  }
  if(!MAP.count(make_pair(E_x,E_y))) cout<<"-1"<<endl;
  else{
    cout<<bfs()<<endl;
  }
  return 0;
}