Given an array of non-negative integers, you are initially positioned at the first index of the array.

Each element in the array represents your maximum jump length at that position.

Determine if you are able to reach the last index.

Example 1:

Input: [2,3,1,1,4]

Output: true

Explanation: Jump 1 step from index 0 to 1, then 3 steps to the last index.

Example 2:

Input: [3,2,1,0,4]

Output: false

Explanation: You will always arrive at index 3 no matter what. Its maximum jump length is 0, which makes it impossible to reach the last index.


from typing import List

class Solution:
    def canJump(self, nums: List[int]) -> bool:
        if not nums: return True

        dp = [-1] * len(nums)
        dp[0] = nums[0]

        for i in range(1, len(nums)):
            if dp[i-1]-1 < 0:
                return False

            dp[i] = max(dp[i-1]-1, nums[i])

        return dp[len(nums)-1] >= 0

Test Cases

test = Solution()
assert test.canJump([2,3,1,1,4]) == True
assert test.canJump([3,2,1,0,4]) == False
assert test.canJump([]) == True
print('All Passed!')

Big O Analysis

Space Complexity: O(N)

Time Complexity: O(N)