back to business

Author: jameszu

Daily-challenge/Dec/28/README.md

@@ -1,83 +1,41 @@
-# Sliding Window Maximum
-You are given an array of integers nums, there is a sliding window of size k which is moving from the very left of the array to the very right. You can only see the k numbers in the window. Each time the sliding window moves right by one position.
+# Reach a Number
+You are standing at position 0 on an infinite number line. There is a goal at position target.
 
-Return the max sliding window.
+On each move, you can either go left or right. During the n-th move (starting from 1), you take n steps.
 
- 
+Return the minimum number of steps required to reach the destination.
 
 Example 1:
-
-Input: nums = [1,3,-1,-3,5,3,6,7], k = 3
-Output: [3,3,5,5,6,7]
-Explanation: 
-Window position                Max
----------------               -----
-[1  3  -1] -3  5  3  6  7       3
- 1 [3  -1  -3] 5  3  6  7       3
- 1  3 [-1  -3  5] 3  6  7       5
- 1  3  -1 [-3  5  3] 6  7       5
- 1  3  -1  -3 [5  3  6] 7       6
- 1  3  -1  -3  5 [3  6  7]      7
+Input: target = 3
+Output: 2
+Explanation:
+On the first move we step from 0 to 1.
+On the second step we step from 1 to 3.
 Example 2:
-
-Input: nums = [1], k = 1
-Output: [1]
-Example 3:
-
-Input: nums = [1,-1], k = 1
-Output: [1,-1]
-Example 4:
-
-Input: nums = [9,11], k = 2
-Output: [11]
-Example 5:
-
-Input: nums = [4,-2], k = 2
-Output: [4]
- 
-
-Constraints:
-
-1 <= nums.length <= 105
--104 <= nums[i] <= 104
-1 <= k <= nums.length<br>
+Input: target = 2
+Output: 3
+Explanation:
+On the first move we step from 0 to 1.
+On the second move we step  from 1 to -1.
+On the third move we step from -1 to 2.
+Note:
+target will be a non-zero integer in the range [-10^9, 10^9].<br>
 
 ## Idea
 Just do while loop and convert to decimal
 
 ## Code
 ```python
 class Solution:
-    def maxSlidingWindow(self, nums: List[int], w: int) -> List[int]:
-        max_left = [0 for n in range(len(nums))]
-        max_right = [0 for n in range(len(nums))]
-        max_left[0] = nums[0]
-        max_right[-1] = nums[-1]
-        
-        for i in range(1, len(nums)):
-            if i % w == 0:
-                
-                max_left[i] = nums[i]
-            else:
-                max_left[i] = max(nums[i], max_left[i-1])
+    def reachNumber(self, target: int) -> int:
+        bound = ceil(sqrt(2*abs(target)+0.25) - 0.5)
+        if target % 2 == 0:
+            if bound % 4 == 1: bound += 2
+            if bound % 4 == 2: bound += 1
+        else:
+            if bound % 4 == 3: bound += 2
+            if bound % 4 == 0: bound += 1
 
-            
-            j = len(nums) - i - 1
-            
-            if j % w == 0:
-                max_right[j] = nums[j]
-            else:
-                max_right[j] = max(nums[j], max_right[j+1])
-        # print(max_right, max_left)
-        lst = []
-        x = 0
-        # j = 0
-        while x + w <= len(nums):
-            # j += 1
-            # print(j)
-            lst += [max(max_right[x], max_left[x+w-1])]
-            x += 1
-            
-        return lst
+        return bound
 
 ```

Daily-challenge/Dec/28/sol.py

@@ -1,32 +1,11 @@
 class Solution:
-    def maxSlidingWindow(self, nums: List[int], w: int) -> List[int]:
-        max_left = [0 for n in range(len(nums))]
-        max_right = [0 for n in range(len(nums))]
-        max_left[0] = nums[0]
-        max_right[-1] = nums[-1]
-        
-        for i in range(1, len(nums)):
-            if i % w == 0:
+    def reachNumber(self, target: int) -> int:
+        bound = ceil(sqrt(2*abs(target)+0.25) - 0.5)
+        if target % 2 == 0:
+            if bound % 4 == 1: bound += 2
+            if bound % 4 == 2: bound += 1
+        else:
+            if bound % 4 == 3: bound += 2
+            if bound % 4 == 0: bound += 1
 
-                max_left[i] = nums[i]
-            else:
-                max_left[i] = max(nums[i], max_left[i-1])
-                
-            
-            j = len(nums) - i - 1
-            
-            if j % w == 0:
-                max_right[j] = nums[j]
-            else:
-                max_right[j] = max(nums[j], max_right[j+1])
-        # print(max_right, max_left)
-        lst = []
-        x = 0
-        # j = 0
-        while x + w <= len(nums):
-            # j += 1
-            # print(j)
-            lst += [max(max_right[x], max_left[x+w-1])]
-            x += 1
-            
-        return lst
+        return bound