Simon's solution to challenge 213

5 files changed, 115 insertions, 2 deletions

diff --git a/challenge-213/sgreen/README.md b/challenge-213/sgreen/README.md
index 4b45deae05..78dadfd6ee 100644
--- a/challenge-213/sgreen/README.md
+++ b/challenge-213/sgreen/README.md
@@ -1,3 +1,3 @@
-# The Weekly Challenge 212
+# The Weekly Challenge 213
 
-Blog: [Jumping Groups](https://dev.to/simongreennet/jumping-groups-2ld2)
+Blog: [Sorting Routes](https://dev.to/simongreennet/sorting-routes-595b)
diff --git a/challenge-213/sgreen/blog.txt b/challenge-213/sgreen/blog.txt
new file mode 100644
index 0000000000..b073d4ad39
--- /dev/null
+++ b/challenge-213/sgreen/blog.txt
@@ -0,0 +1 @@
+https://dev.to/simongreennet/sorting-routes-595b
\ No newline at end of file
diff --git a/challenge-213/sgreen/perl/ch-1.pl b/challenge-213/sgreen/perl/ch-1.pl
new file mode 100755
index 0000000000..f9cdce161f
--- /dev/null
+++ b/challenge-213/sgreen/perl/ch-1.pl
@@ -0,0 +1,14 @@
+#!/usr/bin/env perl
+
+use strict;
+use warnings;
+use feature 'say';
+use experimental 'signatures';
+
+sub main (@array) {
+    # Sort the numbers, evens first
+    @array = sort { $a % 2 <=> $b % 2 || $a <=> $b } @array;
+    say join ', ', @array;
+}
+
+main(@ARGV);
\ No newline at end of file
diff --git a/challenge-213/sgreen/python/ch-1.py b/challenge-213/sgreen/python/ch-1.py
new file mode 100755
index 0000000000..f5ad23bb66
--- /dev/null
+++ b/challenge-213/sgreen/python/ch-1.py
@@ -0,0 +1,15 @@
+#!/usr/bin/env python
+
+import sys
+
+
+def main(array):
+    # Sort the numbers, evens first
+    array.sort(key=lambda x: (x % 2, x))
+    print(*array, sep=', ')
+
+
+if __name__ == '__main__':
+    # Turn the strings into integers
+    n = [int(i) for i in sys.argv[1:]]
+    main(n)
diff --git a/challenge-213/sgreen/python/ch-2.py b/challenge-213/sgreen/python/ch-2.py
new file mode 100755
index 0000000000..786f7f6675
--- /dev/null
+++ b/challenge-213/sgreen/python/ch-2.py
@@ -0,0 +1,83 @@
+#!/usr/bin/env python3
+
+import json
+import sys
+
+
+def find_pairs(nodes, path):
+    '''Find a node with the target that we haven't seen before'''
+    target = nodes[path[-1][0]][path[-1][1]]
+    pairs = []
+
+    for x in range(len(nodes)):
+        # we don't want to search the current node
+        if x == nodes[-1][0]:
+            continue
+
+        for y in range(len(nodes[x])):
+            if nodes[x][y] == target and [x, y] not in path:
+                pairs.append([x, y])
+
+    # Return new pairs (if any)
+    return pairs
+
+
+def find_routes(nodes, path, end):
+    '''Walk through the node and maybe switch node number'''
+
+    # The last value is the current node number we are on
+    current_node = nodes[path[-1][0]]
+    current_pos = path[-1][1]
+    shortest_solution = None
+
+    # Move forward and backwards to see if we can find another node to link to
+    #  or the target
+    for direction in (-1, 1):
+        # The end is 0 when moving backwards, or the number of numbers in this
+        #  node when moving forward
+        end_pos = -1 if direction == -1 else len(current_node)
+        new_nodes = []
+
+        for y in range(current_pos+direction, end_pos, direction):
+            new_nodes += [[path[-1][0], y]]
+            if current_node[y] == end:
+                # We have hit our target, return the solution
+                return path + new_nodes
+
+            # Find out other nodes with this number, that we haven't seen before
+            pairs = find_pairs(nodes, path + new_nodes)
+            for pair in pairs:
+                # Call the function again with the new list of node/number
+                # We use -1 to exclude the current position to avoid dups
+                solution = find_routes(nodes, path+new_nodes[:-1]+[pair], end)
+                if shortest_solution is None or len(shortest_solution) > len(solution):
+                    shortest_solution = solution
+
+    return shortest_solution
+
+
+def main(nodes, start, end):
+    '''Find the shortest route between start and end'''
+    shortest_solution = None
+
+    for x in range(len(nodes)):
+        for y in range(len(nodes[x])):
+            if nodes[x][y] == start:
+                # This is a starting point
+                solution = find_routes(nodes, [[x, y]], end)
+
+                if shortest_solution is None or len(shortest_solution) > len(solution):
+                    # This the shortest solution we have found so far
+                    shortest_solution = solution
+
+    if not shortest_solution:
+        print('-1')
+        return
+
+    # We now have the shortest solution. Turn the x,y pairs into numbers
+    routes = [nodes[x[0]][x[1]] for x in shortest_solution]
+    print(*routes, sep=',')
+
+
+if __name__ == '__main__':
+    main(json.loads(sys.argv[1]), int(sys.argv[2]), int(sys.argv[3]))