Create 27. 4 Keys Keyboard.py

02_Dynamic-Programming/12. DP Using 1D Array/27. 4 Keys Keyboard.py

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+# https://www.lintcode.com/problem/867
+
+class Solution:
+    def max_a(self, n: int) -> int:
+        dp = [i for i in range(n+1)]
+        for i in range(4, n+1):
+            count = 2
+            prev = i-3
+            while prev > 0:
+                dp[i] = max(dp[i], count*dp[prev])
+                prev -= 1
+                count += 1
+        return dp[n]
+
+
+# Time: O(N^2)
+# Space: O(N)