Dec 29

Author: GSNCodes

December_LeetCode_Challenge/Reach_A_Number.py

@@ -0,0 +1,57 @@
+You are standing at position 0 on an infinite number line. There is a goal at position target.
+
+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: 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: 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].
+
+
+
+# O(target^1/2) Time and O(1) Space
+class Solution:
+    def reachNumber(self, target: int) -> int:
+        
+        sum_val = 0
+        steps = 0
+        
+        target = abs(target)
+        
+        while sum_val < target:
+            sum_val += steps
+            steps += 1
+            
+        
+        while (sum_val - target) % 2 == 1:
+            sum_val += steps
+            steps += 1
+            
+        return steps-1
+
+
+class Solution(object):
+    def reachNumber(self, target):
+        target = abs(target)
+        k = 0
+        while target > 0:
+            k += 1
+            target -= k
+
+        return k if target % 2 == 0 else k + 1 + k%2