Print matrix in antispiral form

CServer Side ProgrammingProgramming

Given a 2d array of n*n and the task is to find the antispiral arrangement of the given matrix

Input : arr[4][4]={1,2,3,4,
   5,6,7,8,
   9,10,11,12
   13,14,15,16}
Output: 10 11 7 6 5 9 13 14 15 16 12 8 4 3 2 1

For this, stack can be used where the transpose of a matrix can be pushed inside stack and poped reversely

Algorithm

START
STEP 1 -> declare stack vector element as stk and variables as int r=4, c=4, i, j, rs=0 and cs=0
Step 2 -> store matrix elements in 2-3 array
Step 3 -> Loop For i=0 and o<4 and i++
   Loop For j=0 and j<4 and j++
      Print arr[i][j]
      End
      Print 
   End Step 4 -> Loop While rs<c and cs<r    Loop For i=rs and i<c and i++       Push arr[rs][i]       End       cs++    Loop For i=cs and i<r-1 and ++i       Push arr[r-1][i]    End    c—    IF(cs<r)       Loop For i=r-1 and i>=rs and –i          Push arr[r-1][i]       End       r- -    End    IF(rs<c)       Loop For i=c-1 and i>=cs and i- -          Push arr[i][rs]          End          Rs++       End    End Step 5 -> Loop While !stk.empty() Print stk.top() Call pop() End STOP

Example

#include<iostream>
#include <bits/stdc++.h>
using namespace std;
int main(){
   stack <int> stk;
   int R=4,C=4,i,j,RS=0,CS=0;
   int mat[R][C] = { {1,2,3, 4}, {5,6,7,8},{9,10,11,12},{13,14,15,16}};
   for(i=0;i<4;i++){
      for(j=0;j<4;j++)
         cout<<mat[i][j]<<" ";
      cout<<"
";    }    while(RS<C&&CS<R) {       for(i=RS;i<C;i++)          stk.push(mat[RS][i]);       CS++;       for(i=CS;i<R-1;++i)          stk.push(mat[i][C-1]);       C--;    if(CS<R){       for(i=R-1;i>=RS;--i)          stk.push(mat[R-1][i]);       R--;    }    if(RS<C){       for(i=C-1;i>=CS;i--)          stk.push(mat[i][RS]);       RS++;    } } while(!stk.empty()){    cout<<stk.top()<<" ";    stk.pop(); }

Output

if we run the above program then it will generate the following output

1 2 3 4
5 6 7 8
9 10 11 12
13 14 15 16
10 11 7 6 5 9 13 14 15 16 12 8 4 3 2 1
raja
Updated on 30-Jul-2019 22:30:26

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