solve: jumpGame

Author: yolophg

jump-game/yolophg.py

@@ -0,0 +1,29 @@
+# Time Complexity: O(n) - go through the array once, checking jump reachability.
+# Space Complexity: O(1) - no extra space used, just a few variables.
+
+class Solution:
+    def canJump(self, nums: List[int]) -> bool:
+
+        if len(nums) == 1:
+            # if there's only one element, we're already at the last index
+            return True  
+
+        # start from second-to-last index
+        backtrack_index = len(nums) - 2 
+        # need to jump at least once to reach the last index 
+        jump = 1  
+
+        while backtrack_index > 0:
+            # If we can jump from this position to the next "safe" spot
+            if nums[backtrack_index] >= jump:
+                # reset jump counter since we found a new reachable point
+                jump = 1  
+            else:
+                # otherwise, increase the jump required
+                jump += 1  
+
+            # move one step left
+            backtrack_index -= 1  
+
+        # finally, check if we can reach the last index from the starting position
+        return jump <= nums[0]