Merge pull request Py-Contributors#476 from SOURAB-BAPPA/spiralmatrix

Spiralmatrix

Author: codeperfectplus

Python/Algorithms/README.md

@@ -12,7 +12,7 @@ List of Algorithms in Python contained in this repository
   - [Recursion Algorithms](#recursionalgorithms)
   - [Searching Algorithms](#searchingalgorithms)
   - [Sorting Algorithms](#sortingalgorithms)
-
+  - [Spiral Matrix](#SpiralMatrix)
 ### Backtracking Algorithms: 
 Backtracking is a technique for solving problems recursively by trying to build a solution incrementally, one piece at a time, removing those solutions that fail to satisfy the constraints of the problem at any point of time.
  Example of implementation- Soduku solving.
@@ -52,3 +52,6 @@ Examples of implementation- Binary Search, Linear Search, Fibonacci Search.
 ### Sorting Algorithms:
 A Sorting algorithm is an algorithm that puts elements of a list in a certain order. The most frequently used orders are numerical order and lexicographical order. Efficient sorting is important for optimizing the efficiency of other algorithms that require input data to be in sorted lists.
 Examples of implementation- Quick Sort, Merge Sort. 
+
+### Spiral Matrix:
+The Spiral Matrix problem takes a 2-Dimensional array of N-rows and M-columns as an input, and prints the elements of this matrix in spiral order. The spiral begins at the top left corner of the input matrix, and prints the elements it encounters, while looping towards the center of this matrix, in a clockwise manner.

Python/Algorithms/SpiralMatrix/SpiralMatrix.py

@@ -0,0 +1,44 @@
+def spiral_matrix():
+    i = 0  # starting row index
+    j = 0  # starting column index
+    c = 0
+    print("Please enter number of rows of the spiral matrix:")
+    try:
+        no = int(input())
+    except Exception:
+        print("Please enter numbers only")
+        return 0
+    high = no ** 2
+    val = 1
+    a = [[0 for i in range(no)] for j in range(no)]
+
+    while val <= high:
+        while j < no - 1:  # for first row
+            a[i][j] = val
+            val += 1
+            j += 1
+        while i < no - 1:  # for last column
+            a[i][j] = val
+            val += 1
+            i += 1
+        while j > c:  # for last row
+            a[i][j] = val
+            val += 1
+            j -= 1
+        while i > c:  # for first column
+            a[i][j] = val
+            val += 1
+            i -= 1
+        no -= 1
+        i += 1
+        j += 1
+        c += 1
+        if val == high:  # for odd matrix size
+            a[i][j] = val
+            break
+    print("Spiral matrix is:")
+    for row in a:
+        print(row)
+
+
+spiral_matrix()