Defuse the bomb

Author: volodimyr

1652.defuse_the_bomb/defuse.py

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+# 1652. Defuse the bomb
+# Topics: 'Array', 'Sliding Window'
+# 
+# You have a bomb to defuse, and your time is running out! Your informer will provide you with a circular array code of length of n and a key k.
+
+# To decrypt the code, you must replace every number. All the numbers are replaced simultaneously.
+
+#     If k > 0, replace the ith number with the sum of the next k numbers.
+#     If k < 0, replace the ith number with the sum of the previous k numbers.
+#     If k == 0, replace the ith number with 0.
+
+# As code is circular, the next element of code[n-1] is code[0], and the previous element of code[0] is code[n-1].
+
+# Given the circular array code and an integer key k, return the decrypted code to defuse the bomb!
+
+ 
+
+# Example 1:
+
+# Input: code = [5,7,1,4], k = 3
+# Output: [12,10,16,13]
+# Explanation: Each number is replaced by the sum of the next 3 numbers. The decrypted code is [7+1+4, 1+4+5, 4+5+7, 5+7+1]. Notice that the numbers wrap around.
+
+# Example 2:
+
+# Input: code = [1,2,3,4], k = 0
+# Output: [0,0,0,0]
+# Explanation: When k is zero, the numbers are replaced by 0. 
+
+# Example 3:
+
+# Input: code = [2,4,9,3], k = -2
+# Output: [12,5,6,13]
+# Explanation: The decrypted code is [3+9, 2+3, 4+2, 9+4]. Notice that the numbers wrap around again. If k is negative, the sum is of the previous numbers.
+
+ 
+
+# Constraints:
+
+#     n == code.length
+#     1 <= n <= 100
+#     1 <= code[i] <= 100
+#     -(n - 1) <= k <= n - 1
+
+from typing import List
+
+
+class Solution:
+    def decrypt(self, code: List[int], k: int) -> List[int]:
+        if k == 0:
+            return [0] * len(code)
+        result = []
+        if k < 0:
+            window = None
+            code.reverse()
+            for i in range(len(code)):
+                window = calculate_window(code, i+1, -k, window)
+                result.append(window)
+            result.reverse()
+        else:
+            window = None
+            for i in range (len(code)):
+                window = calculate_window(code, i+1, k, window)
+                result.append(window)
+
+        return result
+
+def calculate_window(code: List[int], start: int, k: int, window: int)-> int:
+    if window is None:
+        window = 0
+        while k > 0:
+            if start == len(code):
+                start = 0
+            window += code[start]
+            start+=1
+            k-=1
+    else:
+        window -= code[start-1]
+        end = start + k - 1
+        if end >= len(code):
+            end = end - len(code)
+        window += code[end]
+
+    return window
+