leetcode994

  1 public class Solution
  2     {
  3         int row = 0;
  4         int column = 0;
  5         int FreshOrangeCount = 0;
  6         int RottenOrangeCount = 0;
  7         int Minute = 0;
  8         Queue<int[]> Q = new Queue<int[]>();
  9         int[,] TagGrid;
 10         public void BFS(int[][] grid)
 11         {
 12             var rottinglist = new List<int[]>();
 13 
 14             while(Q.Count>0)
 15             {
 16                 while (Q.Count > 0)
 17                 {
 18                     var orange = Q.Dequeue();
 19 
 20                     int i = orange[0];
 21                     int j = orange[1];
 22 
 23                     int i_new = -1;
 24                     int j_new = -1;
 25 
 26                     //合法范围:up,down,left,right
 27                     //未访问的:TagGrid[newi,newj]==0
 28                     //新鲜的（grid[i][j]==1）
 29                     i_new = i - 1;
 30                     j_new = j;
 31 
 32                     //up:i-1>=0
 33                     if (i_new >= 0 && TagGrid[i_new, j_new] == 0 && grid[i_new][j_new] == 1)
 34                     {
 35                         FreshOrangeCount--;
 36                         RottenOrangeCount++;
 37                         TagGrid[i_new, j_new] = 1;//visited
 38                         grid[i_new][j_new] = 2;//go bad
 39                         rottinglist.Add(new int[] { i_new, j_new });
 40                     }
 41 
 42                     //down:i+1<=row-1
 43                     i_new = i + 1;
 44                     j_new = j;
 45                     if (i_new <= row - 1 && TagGrid[i_new, j_new] == 0 && grid[i_new][j_new] == 1)
 46                     {
 47                         FreshOrangeCount--;
 48                         RottenOrangeCount++;
 49                         TagGrid[i_new, j_new] = 1;//visited
 50                         grid[i_new][j_new] = 2;//go bad
 51                         rottinglist.Add(new int[] { i_new, j_new });
 52                     }
 53 
 54                     //left:j-1>=0
 55                     i_new = i;
 56                     j_new = j - 1;
 57                     if (j_new >= 0 && TagGrid[i_new, j_new] == 0 && grid[i_new][j_new] == 1)
 58                     {
 59                         FreshOrangeCount--;
 60                         RottenOrangeCount++;
 61                         TagGrid[i_new, j_new] = 1;//visited
 62                         grid[i_new][j_new] = 2;//go bad
 63                         rottinglist.Add(new int[] { i_new, j_new });
 64                     }
 65 
 66                     //right:j+1<=column-1
 67                     i_new = i;
 68                     j_new = j + 1;
 69                     if (j_new <= column - 1 && TagGrid[i_new, j_new] == 0 && grid[i_new][j_new] == 1)
 70                     {
 71                         FreshOrangeCount--;
 72                         RottenOrangeCount++;
 73                         TagGrid[i_new, j_new] = 1;//visited
 74                         grid[i_new][j_new] = 2;//go bad
 75                         rottinglist.Add(new int[] { i_new, j_new });
 76                     }
 77 
 78                 }
 79                 if (rottinglist.Any())
 80                 {
 81                     Minute++;
 82                 }
 83                 foreach (var l in rottinglist)
 84                 {
 85                     Q.Enqueue(l);
 86                 }
 87                 rottinglist.Clear();
 88             }
 89         }
 90 
 91         public int OrangesRotting(int[][] grid)
 92         {
 93             row = grid.Length;
 94             column = grid[0].Length;
 95             TagGrid = new int[row, column];
 96 
 97             for (var i = 0; i < row; i++)
 98             {
 99                 for (var j = 0; j < column; j++)
100                 {
101                     TagGrid[i, j] = 0;//unvisited
102                     if (grid[i][j] == 1)
103                     {
104                         FreshOrangeCount++;
105                     }
106                     if (grid[i][j] == 2)
107                     {
108                         RottenOrangeCount++;
109                         Q.Enqueue(new int[] { i, j });
110                     }
111                 }
112             }
113 
114             BFS(grid);
115 
116             if (FreshOrangeCount != 0)
117             {
118                 return -1;
119             }
120             else
121             {
122                 return Minute;
123             }
124         }
125     }