Demonstrates the use of recursion . Implemetn a blobsize ( 5 by 5) calculator pr

Question

Demonstrates the use of recursion . Implemetn a blobsize ( 5 by 5) calculator program. Here is a sample program dialog for the gird: Enter coordinates for each filled cell; e.g.2 3 Don't enter commas or parentheses. Enter -1 -1 to finish entering cells. input: 1 1          1 2           22          2 3          3 3         3 5         4 1         4 5         5 2         5 4         5 5        -1 -1 output: Grid: X X _ _ _ _ X X _ _ _ _ X _ X X _ _ _ X _ X _ X X Blob sizes: 5 5 0 0 0 0 5 5 0 0 0 0 5 0 4 2 0 0 0 4 0 2 0 4 4 Algorithm to calculate the size of a blob anchored at a givencell 1. Copy the grid. 2. Make a recursive call, using the copy of the grid you madein step 1: If the cell (x, y) is not in the array then          return0 else if the cell(x, y) is empty, then          return0 else         Mark the cell(x, y)as empty        return 1 + the count of(x, y)'s 8 neighbor cells                      (Make 8 recursive calls, one for each neighbor) Demonstrates the use of recursion . Implemetn a blobsize ( 5 by 5) calculator program. Here is a sample program dialog for the gird: Enter coordinates for each filled cell; e.g.2 3 Don't enter commas or parentheses. Enter -1 -1 to finish entering cells. input: 1 1          1 2           22          2 3          3 3         3 5         4 1         4 5         5 2         5 4         5 5        -1 -1 output: Grid: X X _ _ _ _ X X _ _ _ _ X _ X X _ _ _ X _ X _ X X Blob sizes: 5 5 0 0 0 0 5 5 0 0 0 0 5 0 4 2 0 0 0 4 0 2 0 4 4 Algorithm to calculate the size of a blob anchored at a givencell 1. Copy the grid. 2. Make a recursive call, using the copy of the grid you madein step 1: If the cell (x, y) is not in the array then          return0 else if the cell(x, y) is empty, then          return0 else         Mark the cell(x, y)as empty        return 1 + the count of(x, y)'s 8 neighbor cells                      (Make 8 recursive calls, one for each neighbor)

Explanation / Answer

#include<iostream> using namespace std; void print_grid(int grid[5][5]) {    int i,j;
   for(i=0;i<5;i++)    for(j=0,cout<<" ";j<5;j++)    {    if(grid[i][j]==1)    cout<<"X";    else    cout<<"_";           }       } int rec_find_grid(int x,int y,int grid[5][5]) {       if(x<0 || x>=5 || y<0 ||y>=5)       return 0;       else       if(grid[x][y] ==0)       return 0;       else       {       grid[x][y]=0;       return (1+       rec_find_grid(x-1,y-1,grid) +       rec_find_grid(x,y-1,grid) +       rec_find_grid(x+1,y-1,grid) +       rec_find_grid(x-1,y,grid) +       rec_find_grid(x+1,y,grid) +       rec_find_grid(x-1,y+1,grid) +       rec_find_grid(x,y+1,grid) +       rec_find_grid(x+1,y+1,grid ));       } } void size_grid(int grid[5][5]) {    int i,j;    int copy_grid[5][5];    for(i=0;i<5;i++)    for(j=0,cout<<" ";j<5;j++)    {    memcpy(copy_grid,grid,sizeof(copy_grid));    cout<<rec_find_grid(i,j,copy_grid);    } } int main() {    int grid[5][5];       int x,y,i,j;    for(i=0;i<5;i++)    for(j=0;j<5;j++)    grid[i][j]=0; cout<<"Don't enter commas or parentheses. Enter -1 -1to finish entering cells."; cout<<"input :";    do    {    cin>>x>>y;    if(x==-1 && y == -1)    break;    else    {    grid[x-1][y-1]=1;    }    }while(x!=-1 && y!=-1);    cout<<"Grid is : ";    print_grid(grid);    cout<<endl;    cout<<"Size vector is: ";    size_grid(grid);    cout<<endl;    system("pause");
}
/* Sample output Don't enter commas orparentheses. Enter -1 -1 to finish enteringcells.input :1 1    12      2 2    23    33    35    41    45    52    54    55    -1-1 Grid is :
XX___ _XX__ __X_X X___X _X_XX Size vector is :
55000 05500 00504 20004 02044 Press any key to continue . .. Don't enter commas orparentheses. Enter -1 -1 to finish enteringcells.input :1 1    12      2 2    23    33    35    41    45    52    54    55    -1-1 Grid is :
XX___ _XX__ __X_X X___X _X_XX Size vector is :
55000 05500 00504 20004 02044 Press any key to continue . ..
*/

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