Create Jump Game - Leetcode 55.py

Author: gahogg

Jump Game - Leetcode 55.py

@@ -0,0 +1,57 @@
+class Solution:
+    def canJump(self, nums: List[int]) -> bool:
+	      # Recursive Solution
+	      # Time: O(Max(nums) ^ n)
+	      # Space: O(n)
+        n = len(nums)
+        
+        def can_reach(i):
+            if i == n-1:
+                return True
+            
+            for jump in range(1, nums[i]+1):
+                if can_reach(i+jump):
+                    return True
+            
+            return False
+        
+        return can_reach(0)
+
+
+class Solution:
+    def canJump(self, nums: List[int]) -> bool:
+        # Top Down DP (Memoization)
+        # Time: O(n^2)
+        # Space: O(n)
+        n = len(nums)
+        memo = {n-1: True}
+
+        def can_reach(i):
+            if i in memo:
+                return memo[i]
+            
+            for jump in range(1, nums[i]+1):
+                if can_reach(i+jump):
+                    memo[i] = True
+                    return True
+            
+            memo[i] = False
+            return False
+        
+        return can_reach(0)
+
+
+class Solution:
+    def canJump(self, nums: List[int]) -> bool:
+        # Greedy - Start at end
+	      # Time: O(n)
+	      # Space: O(1)
+        n = len(nums)
+        target = n - 1
+
+        for i in range(n-1, -1, -1):
+            max_jump = nums[i]
+            if i + max_jump >= target:
+                target = i
+
+        return target == 0