Merge pull request #1919 from waltman/branch-for-challenge-068

python code for challenge 68

2 files changed, 78 insertions, 0 deletions

diff --git a/challenge-068/walt-mankowski/python/ch-1.py b/challenge-068/walt-mankowski/python/ch-1.py
new file mode 100644
index 0000000000..b2c22a3923
--- /dev/null
+++ b/challenge-068/walt-mankowski/python/ch-1.py
@@ -0,0 +1,38 @@
+def print_mat(m):
+    for row in m:
+        print(row)
+    print()
+
+def zero_mat(m):
+    num_rows = len(m)
+    num_cols = len(m[0])
+
+    row_flags = [False for _ in range(num_rows)]
+    col_flags = [False for _ in range(num_cols)]
+    for r in range(num_rows):
+        for c in range(num_cols):
+            if m[r][c] == 0:
+                row_flags[r] = True
+                col_flags[c] = True
+
+    for r in range(num_rows):
+        for c in range(num_cols):
+            if row_flags[r] or col_flags[c]:
+                m[r][c] = 0
+    
+m1 = [[1,0,1],
+      [1,1,1],
+      [1,1,1]]
+
+m2 = [[1,0,1],
+      [1,1,1],
+      [1,0,1]]
+
+print_mat(m1)
+print_mat(m2)
+
+zero_mat(m1)
+zero_mat(m2)
+
+print_mat(m1)
+print_mat(m2)
diff --git a/challenge-068/walt-mankowski/python/ch-2.py b/challenge-068/walt-mankowski/python/ch-2.py
new file mode 100644
index 0000000000..5f0902ab23
--- /dev/null
+++ b/challenge-068/walt-mankowski/python/ch-2.py
@@ -0,0 +1,40 @@
+class Node:
+    def __init__(self, val):
+        self.val = val
+        self.next = None
+
+def make_list(a):
+    L = Node(a[0])
+    cur = L
+    for val in range(1, len(a)):
+        node = Node(a[val])
+        cur.next = node
+        cur = node
+    return L
+
+def print_list(L):
+    while L:
+        print(L.val, end='')
+        if L.next:
+            print(' => ', end='');
+        L = L.next
+    print()
+
+def reorder_list(L):
+    # save the list in an array
+    a = []
+    while L:
+        a.append(L)
+        L = L.next
+
+    # now reorder things
+    n = len(a)-1
+    for i in range(0, int(n/2)):
+        a[n-i].next = a[i].next
+        a[i].next = a[n-i]
+        a[n-i-1].next = None
+
+L = make_list(range(1,11))
+print_list(L)
+reorder_list(L)
+print_list(L)