Number of Islands

Description:

Given a 2d grid map ‘1‘ of S (land) ‘0‘ and S (water), count the number of islands. An island is surrounded by water and are formed by connecting adjacent lands horizontally or vertically. Assume all four edges of the grid is all surrounded by water.

Example 1:

11110
11010
11000
00000

Answer:1

Example 2:

11000
11000
00100
00011

Answer:3

Code:

1 #defineMAX 5002 3 structVertex4 {5     intRow;6     intCol;7VertexintXinty): Row (x), col (y) {8     }9 };Ten  One classSolution { A Private: - BOOLVisit[max][max]; -  Public: the  -     voidBfstraverse (vector<vector<Char>>& Grid,intIintj) -     { -VISIT[I][J] =true; +Deque<vertex>m; - M.push_back (Vertex (i,j)); +          while(!m.empty ()) A         { atVertex v =M.front (); - M.pop_front (); -             intMrow =V.row; -             intMCol =V.col; -              for(intK =1; K <=4; ++k) -             { in                 Switch(k) -                 { to                      Case 1: +Mrow = v.row-1; -MCol =V.col; the                          Break; *                      Case 2: $Mrow = v.row+1;Panax NotoginsengMCol =V.col; -                          Break; the                      Case 3: +Mrow =V.row; AMCol = v.col-1; the                          Break; +                      Case 4: -Mrow =V.row; $MCol = v.col+1; $                          Break; -                 } -                 if(Mrow >=0&& Mrow < Grid.size () && MCol >=0&& MCol < grid[0].size () the&& Grid[mrow][mcol] = ='1'&& Visit[mrow][mcol] = =false) -                 {WuyiVisit[mrow][mcol] =true; the M.push_back (Vertex (mrow,mcol)); -                 } Wu             } -         } About     } $      -     intNumislands (vector<vector<Char>>&grid) { -size_t row =grid.size (); -         if(Row = =0) A             return 0; +size_t col = grid[0].size (); the          //Note that the initialization of two-dimensional arrays can not be used directly with Visit[max][max] = {false}, should take A For loop (memset function seems to be possible) -          for(inti =0; i < row; ++i) $         { the              for(intj =0; J < Col; ++j) theVISIT[I][J] =false; the         } the         intresult =0; -          for(inti =0; i < row; ++i) in         { the              for(intj =0; J < Col; ++j) the             { About                 if(grid[i][j]=='1'&& Visit[i][j] = =false ) the                 { the++result; the bfstraverse (Grid, I, j); +                 } -             } the         }Bayi         returnresult; the     } the};

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Number of Islands