Given a 2D array, the task is to print matrix in anti spiral form:
Examples:
Output: 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
Input : arr[][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 Input :arr[][6] = {1, 2, 3, 4, 5, 6 7, 8, 9, 10, 11, 12 13, 14, 15, 16, 17, 18}; Output : 11 10 9 8 7 13 14 15 16 17 18 12 6 5 4 3 2 1
The idea is simple, we traverse matrix in spiral form and put all traversed elements in a stack. Finally one by one elements from stack and print them.
Python 3
# Python 3 program to print # matrix in anti-spiral form R = 4 C = 5 def antiSpiralTraversal(m, n, a): k = 0 l = 0 # k - starting row index # m - ending row index # l - starting column index # n - ending column index # i - iterator stk = [] while (k < = m and l < = n): # Print the first row # from the remaining rows for i in range (l, n + 1 ): stk.append(a[k][i]) k + = 1 # Print the last column # from the remaining columns for i in range (k, m + 1 ): stk.append(a[i][n]) n - = 1 # Print the last row # from the remaining rows if ( k < = m): for i in range (n, l - 1 , - 1 ): stk.append(a[m][i]) m - = 1 # Print the first column # from the remaining columns if (l < = n): for i in range (m, k - 1 , - 1 ): stk.append(a[i][l]) l + = 1 while len (stk) ! = 0 : print ( str (stk[ - 1 ]), end = " " ) stk.pop() # Driver Code mat = [[ 1 , 2 , 3 , 4 , 5 ], [ 6 , 7 , 8 , 9 , 10 ], [ 11 , 12 , 13 , 14 , 15 ], [ 16 , 17 , 18 , 19 , 20 ]]; antiSpiralTraversal(R - 1 , C - 1 , mat) # This code is contributed # by ChitraNayal |
Output:
12 13 14 9 8 7 6 11 16 17 18 19 20 15 10 5 4 3 2 1
Time complexity: O(R + C).
Auxiliary Space: O(R + C).
Please refer complete article on Print matrix in antispiral form for more details!
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