BFS小记

  1 #include <iostream>
  2 #include <fstream>
  3 #include <queue>
  4 #include <iomanip>
  5 
  6 using namespace std;
  7 typedef pair<int, int> P;
  8 const int INF = 100000000;
  9 int M;
 10 int N;
 11 int d[256][256] = { 0 };
 12 char maze[256][256] = {0};
 13 int dx[4] = { 1, 0, -1, 0 };
 14 int dy[4] = { 0, 1, 0, -1 };
 15 int sx, sy;
 16 int gx, gy;
 17 int  BFS()
 18 {
 19     queue<P> que;
 20     for (int i = 0; i < N; i++)
 21     {
 22         for (int j = 0; j < M; j++)
 23         {
 24             d[i][j] = INF;
 25         }
 26     }
 27     que.push(P(sx, sy));
 28     d[sx][sy] = 0;
 29     while (que.size())
 30     {
 31         P p = que.front();
 32         que.pop();
 33         if (p.first == gx && p.second == gy)break;
 34 
 35         for (int i = 0; i < 4; i++)
 36         {
 37             int nx = p.first + dx[i], ny = p.second + dy[i];
 38             if ( maze[nx][ny] == ‘G‘ || 0 <= nx && nx < N && 0 <= ny && ny < M && maze[nx][ny] != ‘#‘ && maze[nx][ny] == ‘.‘ && d[nx][ny] == INF )
 39             {
 40                 que.push(P(nx, ny));
 41                 d[nx][ny] = d[p.first][p.second] + 1;
 42             }
 43         }
 44     }
 45     return d[gx][gy];
 46 
 47 }
 48 void solve( )
 49 {
 50     int res = BFS();
 51     cout << endl << res << endl;
 52 }
 53 void solvedata()
 54 {
 55     ifstream filein("data1.txt");
 56     ofstream fileout("outdata.txt");
 57 
 58     int tmp;
 59     int i = 0;
 60     while (!filein.eof())
 61     {
 62         filein >> tmp;
 63         fileout << setw(12) << tmp;
 64         cout << tmp << endl;
 65 
 66         i++;
 67         if (i == 10)
 68         {
 69             i = 0;
 70             fileout << endl;
 71         }
 72     }
 73 }
 74 int main()
 75 {
 76     ifstream filein("data.txt");
 77     int i = 0;
 78     while (!filein.eof())
 79     {
 80         filein.getline(maze[i], 100);
 81         cout << maze[i++] << endl;
 82     }
 83     int m = 0, n = 0;
 84     while (maze[0][n])n++;
 85     while (maze[m][0])
 86     {
 87         for (int i = 0; i < n; i++)
 88         {
 89             if (maze[m][i] == ‘S‘)
 90             {
 91                 sx = m;
 92                 sy = i;
 93             }
 94             else if (maze[m][i] == ‘G‘)
 95             {
 96                 gx = m;
 97                 gy = i;
 98             }
 99         }
100         m++;
101     }
102     cout << "S:" << sx << "  " << sy << "  " << endl;
103     cout << "G:" << gx << "  " << gy << "  " << endl;
104     cout << "m:" << m << endl;
105     cout << "n:" << n << endl;
106     M = m;
107     N = n;
108     solve();
109     return 0;
110 }